Liuhua 11-1 oilfield is the first domestic low-pressure oil well tree pilot test target. In order to increase the reliability and operability of the domestic subsea Christmas tree control system, It is necessary to adapt the direct hydraulic control mode of subsea tree to electro-hydraulic multiplexed control mode. Based on the investigation and analysis of the original oilfield direct hydraulic control system, based on making full use of the original equipment and reducing the reconstruction and construction of the semi-submersible platform, the paper designs and studies the electrical system, hydraulic system and chemical agent system newly added to the domestic subsea tree electro-hydraulic multiplexed control system.