Abstract: Correct selection of subsea Christmas tree system is essential for reducing the cost of deepwater oil and gas development project. Based on extensive investigation and review, we systematically summarize the practical selection method for subsea Christmas tree system. Firstly, the characteristics of subsea Christmas tree, tubing hanger and tree cap are summarized. Secondly, the key selection issues and configuration requirements of tree wellhead connector, subsea valves and subsea monitoring and surveillance instruments are analyzed. Thirdly, the decision methods of material classes, pressure ratings, temperature classifications, product specification levels and performance requirement levels are given. Finally, the application scope of subsea production control systems and installation and workover control systems is described.