城乡一体化是城乡关系发展的必然趋势，是应对城乡发展不平衡、不协调的重要举措。随着城市化进程的不断推进，城乡互动日益密切，从而推动城乡发展不断转型。随着城乡一体化战略的不断推进，城乡之间的因素发生了迅速的变化，从而逐步打破了城乡之间的界限、结构甚至作用机制[ 16]，而长期存在的“二元秩序”引发了“共同（综合）发展”的内生需求。在城市化和工业化的推动下，城乡地域系统趋于协调，功能和结构呈现多维性。生态学学者认为城乡一体化应该实现城乡生态发展不平衡的消除，而地理学学者则认为城乡一体化应该是城乡系统之间的合理空间联系。也有学者根据“流动空间”和城乡对等理论阐明了城乡一体化的内涵，认为在信息技术快速发展的时代，传统因素（如，17,18]. In addition, the connotation of the development of urban-rural integration in accordance with the theory of urban-rural equivalence highlights the “different but equal” nature of urban-rural development. In brief, the integrated development of urban and rural areas should be achieved through the two-way flow of factors and the effective allocation of resources to achieve the interaction and integration of the economic, social and ecological fields of the urban and rural regional systems, and ultimately the development of urban and rural equivalence. The above process also refers to the transformation of the heterogeneous dual structure into a homogeneous monolithic structure, which is essential to the development of urban-rural integration [6].

    As revealed by the above theoretical analysis, integrated urban-rural development is a complex, multi-level and multi-element composite structural system with profound connotations. The core meaning of urban-rural integrated development lies in the premise of ensuring the effective allocation of urban and rural factors and resources in both directions, realizing the co-prosperity and co-existence of urban and rural areas through the benign interaction between urban and rural areas, realizing the multi-dimensional integrated development of urban and rural areas in economic, social, ecological and spatial aspects, and ultimately realizing the equivalence of urban and rural regional systems [9]. The specific connotation is presented below. Urban-rural economic integration means that the marginal rewards of urban and rural areas tend to be equal through the two-way flow and optimal allocation of resources and factors under equal economic policies; urban-rural social integration means ensuring that public services (for example., employment, education, medical care and infrastructure) are of equal significance in urban and rural residents; urban-rural ecological integration is achieved through comprehensive and collaborative management of urban and rural regional systems to achieve a state of high integration and complementarity of urban and rural areas. Urban-rural spatial integration refers to the interaction and integration of urban and rural systems in terms of human, logistic and information flows, which is the carrier and basic condition for urban-rural integrated development.

 2 Application

    Under the goal of regional development, integrated urban-rural development should also achieve a unified process of achieving economic-social-ecological benefits of the urban-rural territorial system and a process of spatially balanced development of the urban-rural territorial system [19]. Accordingly, the theory of regional spatial equilibrium model can be borrowed to construct a spatial equilibrium model of urban-rural integrated development to reveal the inner mechanism of urban-rural integrated development.

因此，我们首先假设在区域城乡一体化发展下，区域内的各种生产要素（包括人口）可以自由流动。区域发展综合发展效益（Σ F M）包括社会效益 F ₁、经济效益 F ₂ 和生态效益 F ₃；如果假设某类发展收益 A M 由土地 B M、劳动力 C M、技术 D M和资本 E M组成在城乡一体化发展下，通过要素的流动和优化配置，城乡地域体系最终可以实现城乡地域体系的人均发展收益均等，即最终实现城乡对等。该模型是区域均衡发展理论思想的延伸，能更有效地解释城乡一体化发展的内在机制[ 22]。根据上述内涵解释，城乡要素双向流动和资源优化配置是实现城乡融合发展的重要前提。首先，相关研究发现，中国的城市化水平仍低于世界可比国家的平均水平[ 23]。二是随着城乡一体化发展水平的不断提高，越来越多的城市现代化要素被配置到农村体系中，表现为资本、技术等要素的净流入。第三，随着乡村振兴战略的实施，农村基本公共服务比重不断提高，表现为公共产品比重不断提高。通过城乡之间要素的流动和优化配置，随着城镇化的不断推进，农村人口在一定范围内趋于减少。通过城市多方面因素的输入和乡村振兴战略的实施，农村地域体系综合发展效率趋于提高，即农村地域体系人均开发效率不断提高，城乡地域体系空间、经济和社会布局优化。由此，城乡地域体系的人均发展效率最终趋于均等化，实现城乡一体化发展。