A multi-mode mobile parallel mechanism with over constrained branch chains was designed, and its degrees of freedom and kinematics were deeply analyzed. When exploring the motion of the parallel mechanism, the influence of the over constrained branch chain on its motion stability was studied, and the motion simulation and physical production were carried out to verify the motion of the mechanism and the realization of each mode. Firstly, according to the analysis of the connection between the constrained branch chain and the platform branch chain, a multi-mode mobile parallel mechanism with constrained branch chain was obtained according to its configuration design. The degree of freedom of the two modes of the mechanism, quadrilateral rolling mode and spherical rolling mode, was analyzed by means of the bar group model. The comparative analysis of the mechanism with or without over constrained branch chains was carried out, the centroid coordinates were solved according to ZMP theory, the relationship between the mechanism with or without over constrained branch chains and the angle was compared and analyzed, and Matlab was used to carry out comparative analysis of the centroid situation of the mechanism with motion. Finally, the kinematic simulation of the mechanism was carried out by ADAMS, and the prototype was made to verify the movement of the mechanism and the realization of each mode.