Abstract:  The production platform with three columns is a new type of platform. It has good economical efficiency, safety and reliability, and can perform production and drilling in deep water. Compared with the traditional semi-submersible platform with four columns, the new type platform holds the advantages of high utilization and low total cost. According to the characteristics of the semi-submersible platform, we study the general layout of topside of the three-column platform, which can reserve technology for the future development of the deepwater marginal oilfield in the South China Sea, and provide reference for the design of similar platforms.