The impact of changing of momentum in forklift lifting process is one of the important reasons that leading to the failure of the lifting cylinder, for goods the lifting cylinder lift is very heavy and the collision time of the lifting cylinders piston and end cap is short, the impact force in the collision process is large. And the lifting action of the lifting cylinder is frequent, so the lifting cylinder is easily damaged. In order to reduce the impact force in the lifting process of cylinder, a method was put forward of bypass throttle through the analysis of the cause of the impact force. On the basis of the theoretical analysis, mathematical model was established, and analyzed with AMESim simulation. The conclusion shows that this method can reduce the impact force in the lifting process to half of the original system, and the energy loss is reduced.