Abstract: At present ordinary method of kinematic analysis is not applicable to solve problems of plane mechanism of any complex “Assur Group”.The author suggested to disconnect certain internal pair in the Assur Group in order to convert it into a simple one, and then investigated the movement of the disconnected pair by the aid of the general characteristics of motion of mechanism, finally, solution of movement of original Assur Group will be obtained. In addition, the author detailed the main characteristics of motion of mechanism and these may inspire to introduce some new method in kinematic analysis.