Abstract: As stratified sea-use rights continue to develop, marine management is expected to evolve toward comprehensive three-dimensional marine spatial planning. Existing research remains concentrated at project and micro scales. This paper explains the necessity of three-dimensional planning from the perspectives of high-quality marine development, optimized allocation and overall organization of three-dimensional resources, and intensive use of nearshore space. It constructs a framework spanning functional, temporal, developmental, and rights dimensions, then proposes an overall technical approach. Key relationships concern three-dimensional and two-dimensional planning, stratified use, and planar and vertical functions. Priority tasks include surveying current stratified use, evaluating suitability, organizing three-dimensional functions and space, and formulating use-control rules.