Space deployable mechanisms have been widely employed in modern spacecraft, and the dynamic performance of such mechanisms has become increasingly important in the aerospace industry. This article focuses on the dynamic performance of a deployment mechanism with clearance considering damping, friction, gravity, and flexibility. The modeling methods of revolute joint with clearance, close cable loop, and lock mechanism of a typical deployable mechanism are provided in this article. Based on these proposed methods, the dynamics model of a space deployable mechanism with clearance is established using the multi-body program ADAMS. The effects of clearance, damping, friction, gravity, and flexibility on the dynamic performance of a deployable mechanism in the deploying and locking processes are studied using simulations. The results reveal that the deployable mechanism exhibits evidently nonlinear dynamic characteristics, thus validating the significance of clearance, damping, friction, gravity, and flexibility in system dynamic performance.