Since the posture of portable exoskeleton is consistent with human motion and each joint degree of freedom is same, on the basis of DOF coupling in portable exoskeleton, the finite element analysis of the mechanical structure in portable exoskeleton has been calculated. According to the anthropomorphic mechanism design method, the universal joint structure has been used to meet the requirements of degrees of freedom in the mechanical structure of the exoskeleton; using the Hydraulic cylinder to simulate the contraction or stretch of human muscle, and the three-dimensional model of the exoskeleton mechanical systems has been created with the Solidworks software; selecting Human CAD software and setting the parameters of the movement of the human body model, the variations of the various joints can be obtained; using the Parasolid as the standard format for data transfer between the two software Solidworks and ANSYS, the finite element analysis model was established, and according to the principle of coupling, the three translational DOF and two rotating DOF was coupled, besides through both legs vertical standing, one knee kneeling, and one leg vertical standing three conditions, the exoskeleton strength was analyzed. The simulation results show that under the three conditions, a concentrated stress all has been found in the exoskeleton structure, besides the concentrated stresses all have been obtained in the cross-section changing site or the junction of the two components, which stress values exceeded the allowable stress values of the aluminum alloy material, so the suggestions for improvement of the structure are put forward in the article; at the same time, the simulation results provide a numerical basis for the optimization of the portable exoskeleton structure.