In recent years, China’s industrialization and urbanization have entered a new transformational stage of development. The contradictions between innovation-driven development and institutional constraints are intensified, and the problems of resource shortage and inefficiency of resource allocation are becoming increasingly prominent. Therefore, multiple planning integration that merges economic and social development planning, urban spatial planning, and land use planning into an overall planning system has received wide attention from academics and governments at all levels. Promoting multiple planning integration and innovating the theories and technical methods of regional planning, as well as constructing the spatial planning system of national territory with Chinese characteristics, have become an important issue in further reform. This study analyzed the practical problems of planning segregation and essential characteristics of multiple planning contradictions and discussed the strategic positioning of multiple planning integration. Then we constructed a basic theoretical framework of multiple planning integration with “three primaries” and “three separations”. Finally, the technical approaches and long-term mechanisms for gradual multi-plan adjustments were proposed. It can be concluded that the essence of multiple planning integration is to integrate and coordinate all plans at the strategic level of regional spatial structure optimization, and guide the optimization of urban-rural land allocation so that it can achieve spatial consistency, functional integration, and coordination in the development process. Multiple planning integration is neither to prepare a plan nor to focus on solving the greatest common divisor of existing multiple plans, but to promote the formation of a regional planning system with the characteristics of overall-and sub-planning, clear hierarchy, and functional specificity.