In order to improve the current prefabricated building prefabrication rate calculation, and to solve the problems of low efficiency and large error existed in the manual calculation, this study applies the BIM technologyto achieve the automatic statistics of precast concrete components and automatic calculation of precast rate for a PC building based on its BIM model through the secondary development on Revit, which verifies the feasibility of calculating PC building precast rate based on Revit platform. Based on the results of secondary development in this paper, the construction cost can be estimated directly when selecting different combinations of prefabrication rates, and then the prefabrication schemes within acceptable cost range can be selected, to increase economic benefits, and to provide decision-making basis for decision makers to formulate prefabrication schemes.