Based on wearable exoskeleton system, firstly a mechanical model of manmachine system is established, then a dynamics model of the mechanical model is built by the way of principle of virtue work. MATLAB was used to make a dynamics simulation and calculation of the mechanical model. At last, ADAMS was used to prove the dynamics simulation of the redundant mechanism, and also the results between the theoretical calculation and the simulation were analyzed and contrasted. Thus the validity and feasibility of this theoretical analysis are proved.