As a new mainstream building model in the future, prefabricated buildings have the advantages of improving building quality and efficiency, reducing energy consumption, etc., which are helpful to comprehensively improve the modernization level of my country's construction industry, and improve environmental and social and economic benefits. In the development of prefabricated buildings, expensive construction costs are an important factor restricting the development of prefabricated buildings. How to effectively solve the cost control problem of prefabricated buildings is a problem that construction industry practitioners need to solve. Quoted residential engineering cases, compared the cost of prefabricated buildings and cast-in-place buildings, analyzed the difference in the cost structure of the two, the targeted cost control measures were proposed to provide thinking and suggestions for Party A to reduce costs and increase efficiency of prefabricated buildings.