Abstract: Biodiversity is the foundation of regional sustainable development. Accurate evaluation of the spatial pattern of regional biodiversity maintenance functions is of great significance for reflecting the status, changes, and threats of regional ecosystems, as well as selecting corresponding protection strategies. Based on the regional biomass, topography, climate and land cover, a comprehensive assessment model of biodiversity maintenance functions was constructed and applied in Beijing-Tianjin-Hebei region. The results show that: (1) The model can reflect the spatial pattern of biodiversity maintenance functions in Beijing-Tianjin-Hebei region. The high-value areas were mainly concentrated in the Yanshan and Taihang mountains, while the low-value areas were mainly concentrated in the Bashang Plateau and Plain areas. The evaluation results are in line with the actual conditions of the study area. (2) There is a significant correlation between the simulation results and the investigated biodiversity of the counties as well as species diversity in natural reserves. Among the various indicators of biodiversity for counties, the correlation between species-specific and the evaluation results was the highest (r=0.699, P < 0.001), followed by ecosystem type diversity (r=0.680, P < 0.001), richness of rare and endangered species (r=0.571, P < 0.001), richness of wild vascular plants (r=0.544, P < 0.001), alien species invasion (r=-0.437, P < 0.001), and richness of wild higher animals (r=0.404, P < 0.001); The logarithmic correlation between species diversity in natural reserves and evaluation results is the most significant (r=0.540, P < 0.001). About 70% of natural reserves were distributed in the area with extremely important or highly important biodiversity maintenance functions. The evaluation method is applicable for reflecting the function of biodiversity maintenance from the regional scale and the grid level, and for providing scientific basis for the construction of regional nature reserves and ecological restoration.