Aiming at the abnormal falling velocity of the anti-collision truss of the Three Gorges ship lift,we study the influence rule of three factors including the throttle area of the oil return port,the friction resistance of the truss and the deceleration point of the descending stroke of the truss on the falling velocity of the anti-collision truss.By establishing the mechanical model of the falling action of the anti-collision truss,combining with the hydraulic system,mechanical mechanism and electrical control principle of the anti-collision truss,we adopt the mathematical equation modeling and AMESim simulation analysis method to obtain the influence rule of three factors on the falling velocity of the anti-collision truss theoretically.The results show that the throttle area of the oil return port,the friction resistance of the truss and the deceleration point of the descending stroke of the truss all can obviously cause the abnormal falling velocity of the anti-collision truss,which can provide references for the similar projects.