Abstract: In order to study the influence of uncertain parameters on the dynamic response of the parallel mechanism with joint clearances, the 3-RRPaR redundant parallel mechanism was taken as the research object, and the dynamic model of the redundant parallel mechanism with dry friction clearances considering uncertain parameters was established. The dynamic response of the mechanism was analyzed. Firstly, the dry friction contact force model at the clearance of three-dimensional revolute joint is derived by combining the Flores continuous contact force model and the Brown-McPhee friction model. The dynamic model of 3-RRPaR redundant parallel mechanism with dry friction clearances is established by using the first Lagrange method, and the validity of the model was verified by prototype test. Combined with the chaotic polynomial algorithm, the dynamic model of the redundant parallel mechanism with dry friction clearances considering uncertain parameters was established. The influence of uncertain clearances value and friction coefficient on the dynamic response of 3-RRPaR redundant parallel mechanism with dry friction clearances was studied, and the validity of the model was verified by Monte Carlo method. This study provides a theoretical basis for the design and optimization of parallel mechanism.