In this paper, retrofit costs and relative building parameters of masonry structures in Shaanxi, Shanxi, and Sichuan Provinces were collected, to enable a retrofit cost estimation model for masonry structure buildings to be developed. A regression and validation database, including the retrofit cost estimation models of 35 buildings, was built, and the building parameters which influence retrofit costs analyzed. Then, based on the multiple linear regression method, four models were established using the existing retrofit data with SPSS analysis software. After evaluating the four models according to their corresponding evaluation criteria, an optimal rapid estimation model for the retrofit cost of masonry structures was proposed and verified. The results show that the regression model meets the precision requirements and could be valuable in practical engineering.