The ecological systems theory points out that individual development is the result of the interaction between an individual and the environment [30]. As a part of a microsystem, a school is an important living environment in the process of adolescent growth, which will have a profound impact on students’ psychological state and behavioral development [31]. This study will attempt to explore the specific impact of an important element of the school—the school climate—on school bullying. School climate research had its beginnings in the 1930s, when Kurt Lewin [32] first explored the interaction between individuals and their environment from a psychological perspective, opening the way for research on the effects of the school climate. Hoy and Hannum [18] believed that the school climate unites the characteristics of the school environment, which can be perceived by school members, has an important impact on their psychology and behavior, and has relative stability. According to the symbolic interaction theory, individuals grow and develop in interaction with the environment [33], and students are inevitably affected by the school climate during their interaction with the school. The school climate can be characterized by competition or cooperation [34]. Research has shown that there are obvious differences in the impact of different types of school climate on school bullying [35]. Good teacher–student relationships and solid peer relationships have been associated with students’ perceived positive school climate [19,36], which has a significant effect on the prevention of school bullying. In contrast, a school climate that emphasizes competition may promote school bullying, which students use as a means of coping with intense competition [22]. Competition process is like a game of resource acquisition. In the absence of external constraints, individuals are likely to resort to unethical behaviors (e.g., bullying, violence, etc.) to compete for limited resources [37], which in turn exacerbates the occurrence of school bullying. The theory of social domination also supports this view that students resort to bullying in order to gain higher power and status among their peers [38]. Vocational education, as one of the types of education most closely linked to the labor market [39], and the competitive mechanisms of the labor market have also subtly influenced the school climate of secondary vocational schools for a long time. In other words, a competitive school climate is likely to have some influence on bullying in secondary vocational schools.

School belonging mainly refers to the degree of acceptance, respect, and identification that students perceive in school, and can reflect an individual’s emotional connection to the school [40]. A higher sense of school belonging can enable students to have more positive emotions, enhance their attachment to the school [41], help them achieve a positive self-evaluation [42], and promote higher academic performance [43]. School climate is highly correlated with school belonging, and a favorable school climate can help students to have more positive experiences of school, which in turn promotes the formation of students’ sense of belonging to the school [44]. Students with a strong sense of school belonging often have a harmonious peer relationship, have greater trust in teachers, and are more willing to abide by the regulations of the school, which can alleviate the negative impact of a negative school climate to some extent. Studies have shown that school belonging is also significantly negatively correlated with school bullying, and strengthening the sense of belonging to a school has an important preventive and controlling role in reducing bullying behavior among adolescents [45]. A study based on a sample of 6176 Chinese primary school students found that a positive school climate can enhance the sense of school belonging, thereby reducing bullying on campus [46]. A review of studies based on school belonging also found that school belonging was positively correlated with students’ social adaptation, psychological well-being, and self-concept, and negatively correlated with delinquent behaviors such as school bullying [47]. School belonging is likely to mediate the link between school climate and school bullying.

Gender differences in bullying in schools have received widespread attention from scholars. Studies have shown that the probability of bullying in different genders is not the same. Most of the evidence shows that the bullying rate of boys is higher than that of girls [48]. Boys are more likely to suffer from physical bullying and girls are more likely to suffer from relational bullying [49]. A large-scale survey based on 114,290 primary and secondary school students in 15 provinces and cities in China shows that the incidence of school bullying among boys is higher than that among girls [50]. The Education Longitudinal Study (ELS: 2002) conducted by the National Center for Education Statistics (NCES) in the United States of America shows that students attending co-educational high schools suffer more bullying than those in single-sex high schools, with boys attending co-educational high schools experiencing the highest rates of school bullying [51]. However, there are dissenting voices, with a study based on the 2011–2019 American Youth Risk Behavior Survey showing that girls have a higher incidence of both traditional bullying and cyberbullying than boys [52]. In addition, the results of a survey from Kenya showed that all-boy schools were less likely to report bullying than all-girls or co-educational schools [53]. Evidence from China’s vocational schools shows that although the incidence of bullying among boys is significantly higher than that among girls, the trend is for the proportion of bullying in schools for girls to overtake that of boys [54]. These findings not only reflect gender differences in school bullying across cultures and backgrounds, but also indicate the need to study gender differences in secondary school bullying based in the Chinese context. In addition, perceptions of the school climate and sense of school belonging differed by gender. Under the influence of Chinese traditional culture, boys have stronger self-esteem and higher desire for success [55]. They often hope to show self-confidence and independence through aggression [56], while girls rely more on social interaction with the outside world to meet their emotional needs and are more sensitive to external feedback [57]. That is to say, girls are more susceptible to the influence of the school climate, and boys’ sense of school belonging is significantly lower than that of girls. That means gender is likely to have a role in moderating the effects of school climate and school belonging on school bullying.

There has been some research on school bullying using PISA survey data. School bullying in 71 countries based on PISA 2018 found that the problem of school bullying is still prevalent worldwide [58]. Comparing the differences between PISA 2015 and PISA 2018 data, it was found that the problem of school bullying among adolescents in China and Japan has improved significantly, while school bullying among adolescents in the USA and the UK has become more serious; there is no significant change among South Korean adolescents [59], which may be related to the different social cultures, government governance, and school climate in the different countries. The school climate is an important variable that cannot be ignored when studying school bullying. Based on the PISA 2018 data, a comparison of 64 countries shows that a cooperative school climate plays a protective role in school bullying [60]. Cross-cultural research on Chilean and South African students also provides evidence that a positive school climate can reduce school bullying [61]. In addition, studies based on PISA data from the United States, Australia, and other countries have indicated that school belonging is correlated with school bullying, and school belonging can mitigate the negative effects of school bullying to a certain extent [62,63]. Chinese studies using PISA data have also addressed the relationship between school climate, school belonging, and school bullying. The results show that, in the context of Chinese schools, a positive school climate helps to reduce school bullying [64], and school bullying has a weakening effect on school belonging [65]. However, the relevant research is either aimed at general education students or focuses on a cooperative school climate; there is no direct research on the impact of a competitive school climate on the bullying of secondary vocational students. From an international perspective, existing research based on the PISA data is relatively comprehensive, but there is a lack of research on Chinese vocational school students. The existing research on the sample of Chinese vocational education students only focuses on the current situation of school bullying [66]; empirical studies have not been conducted on the correlation mechanism between a competitive school climate and school bullying.