Abstract: In view of the frequent internal leakage of the control valve in the actual operation of a deep water gas field in South China Sea, the valve control mode was changed and the liquid hydrocarbon buffer tank was added in combination with the characteristics of high pressure, large gas flowrate but relatively small liquid flowrate. The on-off control valve is considered for use, and the frequency of the valve before and after the transformation was optimized so as to reduce the valve opening frequency and prolong the service life of the control valve. Finally, the problems of internal leaking for control valve, high cost of maintenance and air pollution are solved. The above analysis results have guiding significance for the subsequent control valve selection of similar high-pressure gas fields.