Buildings that were put into use in the early stages have severe aging of some components, and their seismic performance cannot meet the requirements of current standards. It is urgent to carry out seismic reinforcement and upgrading and renovation. Due to the fact that the renovation of existing buildings relies on the original main structure, involving a large number of concealed components and complex pipelines, the construction space is limited, and the pricing logic is significantly different from that of new construction projects. Therefore, it is not possible to directly apply the pricing concept of new construction projects, which greatly increases the difficulty of implementing cost pricing. In view of this, the article combines an existing building's overall seismic reinforcement and upgrading project, systematically sorts out the existing difficulties in accurate pricing practice, and proposes targeted optimization strategies for reference by peers in the industry.