To reduce the probability of aircraft cargo door opened accidently caused by abnormal stress, the dynamic characteristics of multi-linkage lock mechanisms with kinematic pairs clearance are studied in detail. The equivalent joint clearance link (the length is e) is used to describe the influence of kinematic pairs clearance. Meanwhile, the dynamic analysis model of multi-linkage lock mechanisms is built based on the Lagrange kinetic equation and the screw theory, and the procedures programmed by MATLAB are used to solve and analysis the model. Results indicate that the kinematic pairs clearance has a bigger influence on angular velocity of the rod, angular acceleration of the rod, driving moment and hinge binding kinematic, and the greatest influence appears near the singular configuration. While e is 10 μm, its impact on dynamics of the multi-linkage lock mechanisms is small, however while e is 100 μm, the impact is enhanced obviously.