Electrohydraulic control is a control mode applied widely in current deepwater oil and gas field. Subsea electrohydraulic control system was analyzed. The main hydraulic parameters such as operation pressure, HPU accumulator’〖KG-*2〗s volume, subsea accumulator's volume,were calculated. Based on the South Sea oil and gas field engineering practice, subsea electrohydraulic control system charging pressure simulation model was established by the application of AMESim, simulating the effect of different umbilical cable diameter on filling pressure and ESD. AMESim simulation software was used to make typical working conditions modeling and dynamic simulation for South Sea oil field hydraulic control system. The simulation results show that the performance parameters of the hydraulic system meet the requirements of the corresponding standard specification and engineering.The simulation research provides reference and guidance for umbilical cable diameter selection and subsea hydraulic control system's key component analysis and choosing.