The friction was disposed as an external non-inertia force, and a mended Appell equation including the friction of system was put forward. The kinematic characteristics of a planar closed-loop five-bar mechanism were analyzed by using the method of kinematic influence coefficient. The dissipation function of the mechanism system was proposed, then the generalized dissipation forces were deduced. The dynamics model of the mechanism which included the joint friction was proposed by means of the mended equation. And arithmetic was presented to solve these equations. The results of inverse dynamics testified the correction of the model. The outcomes of simulation indicated that joint friction has obvious influence on motion parameters of the mechanism.