This paper based on the theory of random process, puts forward a probabilistic statistics model ofmechanism kinematics under stationary and nonstationary condition, and compares it with the researchresult of work1. We find that the model supplied by this paper is more accurate than work1. We gavefurther a model of the moving precision ineffectiveness of the mechanism. Based on this model one can es-timate in advance the probabilistic characteristics and reliability of every different kind of mechanism un-der movement. It must be profitable for reliability design.