In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism, it is necessary to study the dynamic characteristics of contact impact force model with the variable stiffness and damping coefficient. Firstly, the parameters in the output process of the system are solved by describing of the flexible joint clearance. Then, based on Lankarani-Nikravesh contact force model, the contact impact stiffness and damping coefficient is modified from fixed values to time-varying coefficients. The dynamic model of spatial linkage weft insertion mechanism with modified clearance is established by Lagrange method, and the dynamic characteristics of the system are calculated. The results show that the joint clearance can directly affect the output performance of the mechanism. With the increase of the clearance value, the curve fluctuations of acceleration, driving torque and collision force are obvious, and it will be further intensified with the increase of spindle speed, which greatly affects the stability of mechanism and fabric quality. Finally, the virtual prototype is established by the SolidWorks software and simulated by the ADAMS software. The simulation results are compared with the numerical results, which verifies the accuracy of the modeling method in this paper.