Abstract: Effectively identifying and evaluating the differences in the temporal and spatial variation of resource carrying capacity in each tidal flat area is conducive to the scientific planning of tidal flat resources. This is of great significance to the realization of rational utilization and protection of coastal tidal flat resources. Based on the spatial variation of semi-closed gulf beaches' characteristics in Bohai Bay and the "driving force-state-impact" model, an evaluation system for the development carrying capacity of tidal flat resources is constructed. The resource carrying capacity of seven evaluation units during four typical years is evaluated, revealing the temporal and spatial evolution characteristics of the development carrying capacity of the tidal flat resources in the bay. The results indicate that the reclamation project weakens the development carrying capacity of the tidal flat in Bohai Bay. During the large-scale construction of the project (2003—2012), the carrying capacity of each evaluation unit has exhibited a downward trend. Due to the implementation of national reclamation control measures, the carrying capacity has demonstrated a recovery trend since 2012. Spatial analysis reveals that the carrying capacity of the bay roof decreased more than that of the southern part of the bay, the carrying capacity of the area near Tianjin Port is poor both before and after the development, and the carrying capacity of the tidal flat breeding area south of Huanghua Port is strong.