In order to increase the reliability and operability of the control system of domestic subsea Christmas tree, the subsea control system modes are compared and analyzed, and the electro-hydraulic composite control method is selected as the control means of the pilot test. The direct hydraulic control system is used in Liuhua 11-1 oil field, it needs to be adapted on the basis of the direct hydraulic control mode. Through the investigation of the direct hydraulic control system of the oil field, on the premise of making full use of the original equipment and minimizing the renovation and construction of the semi-submersible platform, the new electrical system, communication system, hydraulic system and chemical agent system of the electro-hydraulic composite control system are designed, studied and analyzed. Through 4 special calculations and analysis, it is shown that the results meet the requirements of the system, thus demonstrating the feasibility of the design.