WHAT IS ALREADY KNOWN ABOUT THIS TOPIC? An increasing number of studies have projected temperature-related mortality, but few consider the change of population's adaptability to future temperature and mortality burden from cold and heat effects. WHAT IS ADDED BY THIS REPORT? This study offers a comprehensive characterization of human adaptability and excess mortality burden of temperature across various regions of China. WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE? The temperature-related excess mortality was projected to increase in the 2050s and decrease in the 2080s. Heat adaptability was projected to increase in the future, but along with the rising temperatures, the heat-related excess mortality continuously rose, except for the low-speed rising scenario. Although the excess mortality of cold was projected to decrease in the nearer future, it might not keep declining in the long run, due to the decreasing cold-adaptability, which deserves more attention.