The damping characteristic of throttle valve of feedback circuit in pressure compensation system is discussed and the working principle of pressure compensation is analyzed in this paper. In order to illustrate the necessity of the existence of the throttle valve and the effect of throttle valve diameter on the stability of pressure compensation system, the system is modeled in AMESim. Through simulation and analysis, we get such a result: hydraulic shocks can be weakened without affecting its speed of response by setting a reasonable diameter of the throttle valve which plays an important role in keeping the stability of the whole system.