The control valve is the most important implementation part of the high pressure common rail system, and its flow characteristics have a great influence on the performance of the injector. In this paper，based on the structure and the working principle of electromagnetic injector in high pressure common rail system, the simulation model of the injector is established by AMESim software. The key parameters of the control valve, including the volume of the control chamber, the diameter of the Oil inlet hole, the hole diameter of the oil outlet and the hole diameter of the oil diffusion hole, are studied by using the model. The results show that these key structural parameters of the control valve have a great influence on the establishment of the control chamber pressure and the action of the needle valve, Within a certain range, when the control chamber volume is small, the control chamber pressure changes rapidly, the needle moves quickly, the system reacts quickly; increasing the diameter of the control valve inlet hole facilitates the closing speed of the needle valve but reduces the opening speed of the needle valve; increasing the diameter of the hole, the valve opening speed, closing delay time substantially unchanged; increasing the diameter of the oil diffusion hole, the needle closing time increases, the fueling duration is prolonged and the fuel injection quantity increases. On the basis of this, the cavitation problem at the sealing seat of the control valve sleeve in the common rail injector is simulated by CFD simulation, and the process of cavitation is deduced. In the existing structure It is possible to reduce the cavitation phenomenon by increasing the length of the oil diffusion hole of the control valve.