Abstract:The normal operation of the rotor system requires proper clearance. The clearance was changed in the rotor system by manufacturing error, fixing error and wear in the course of using, so it is very important to research on the clearance system which affected the mechanical system work normally. The three typical modeling methods were introduced for the mechanism with clearances, such as the continuous contact model, separationcontact model with two states and the contactsseparationcollision model. Advantages and disadvantages and applicable condition of different models were analyzed, and solving method for each model was summarized. Dynamics experiments and achievements obtained on the representative mechanism with clearances in domestic and from abroad were reviewed. At the end, the main present field of research of it is summarized, and the research in the future is prospected.