The structure of a proportional solenoid valve for automatic transmission is introduced. The design, analysis methodology and dynamic performances of the valve are discussed. Based on the structural analysis of the valve, the operating principle is investigated. Four subsystems that are electric field, magnetic field, mechanical, and hydraulic of the proportional solenoid valve are divided, and their inherent coupling interactions are investigated. The mathematical model of the dynamic performance of the four subsystems is built separately and simulation analysis is carried out. The active process of the proportional solenoid valve is studied by combining with experimental results, verified the correctness of the coupling simulation model. It would be useful for proportional solenoid valve optimal design by analyzing the internal parameters dynamic changes of the valve. In the hydraulic subsystem, the inlet port using ball popper and the nozzle flapper valve for the outlet port. Pressure regulating can be realized by flow control via controlling the opening degree of the outlet. The research results show that the proportional solenoid valve has a small displacement(0.2 mm) in the instantaneous moment of opening, with an open response time less than 2 ms and pressure response time less than 4 ms,it is suitable for automatic transmission control.