We have developed a Mainland China Composite Damaging Earthquake Catalog (MCCDE‐CAT), which contains seismic source and socioeconomic damage information, population exposure, and seismic intensity maps of earthquakes that occurred from 1950 to 2018. The completeness and consistency of the data in past damaging earthquake catalogs are crucial to better understanding the damage to our social and economic system from future earthquakes. Although many disaster databases are currently available worldwide, they show a serious lack of data and no consistency. To develop the MCCDE‐CAT, we cross‐checked and integrated earthquake damage information based on six kinds of earthquake catalogs for Mainland China. Missing information in these catalogs was supplied from records in journal publications and reports published by the government and relevant institutions. We also performed a statistical analysis of the data in the MCCDE‐CAT and preliminarily discuss the temporal and spatial characteristics of earthquake disasters and socioeconomic losses in Mainland China. The MCCDE‐CAT will contribute to loss estimation for damaging earthquakes, earthquake‐related product pricing in the reinsurance industry, and other related fields. More importantly, the MCCDE‐CAT will be publicly accessible and provide a basis for researchers to pursue other earthquake disaster‐related studies.