In order to improve the ability of carrying heavy loads and reduce the energy consumption of soldier under the way of exercises，a wearable exoskeleton robot driven by hydraulic pressure was designed, with the lower extremity exoskeleton robot having twelve degrees of freedom (12DOFs). According to its function and working principle， the key parts in the structure were analyzed, and the sizes of each part of the exoskeleton robot were designed. The exoskeleton robot modeling was performed by the finite element software, the finite element statics simulation was used on the exoskeleton robot，and the transient dynamics simulation of thigh was carried out. Through the simulation study and analysis， the rationality of mechanism design is verified，which provides the reference for the further study of the exoskeleton robot.