The mathematical model and the simulation model of the proportional throttle valve used in the oilair lubrication system were established by the analytic software AMESim,. The dynamic flow force and the fluid resistance were calculated. The influences of the damping hole, the input signal and the viscous friction coefficient on the performance of the proportional throttle valve were analyzed by the numerical simulation method. The results show that when the flow in the throttle valve is small, the dynamic characteristics of the proportional throttle valve is influenced largely by the hydraulic power,and the instability of the hydraulic power results in a nonlinear relationship between the proportional throttle valve and the input signal. In addition, a reasonable dimension of damping hole is obtained under the condition of the throttle valve in stable operation. With increasing the viscous friction coefficient, the system response frequency decreases,which influences the displacement of the valve core and the total flow.