Abstract: Dry tree semi-submersible platform has become research focus in ocean engineering area in recent years. In this paper, the study is focus mainly on dry tree semi-submersible with four-column and four-pontoon used in South China Sea. Main dimensions design are carried out aiming at the requirements on dry tree production, and heave motion of the platform is controlled by controlling the heave wave frequency peak and heave natural cycle period. On the basis of this, the main dimensions of the platform are designed. In addition, with the dimension data, stability and motion of the platform are analyzed. The analyzing results show that the stability ability of designed dry tree platform could meet the codes requirements, and the motion performance is excellent, which can meet the requirements for the production with dry tree platform. Further study should be conducted through numerical simulation and model testing about topsides installation design, mooring system design and motion of this platform in the future.