Abstract: With regard to assistive exoskeletons, the human-robot misalignment factors in 1-DOF (degree of freedom) human-robot interactions are analyzed, and a model of human-robot misalignment variables is set up. By applying the self-aligned mechanism design methods, an exoskeleton is designed to improve the performance of the human-robot couplings. Firstly, a single DOF biological joint of human body is deeply analyzed. Based on the simplified human being model and the human-robot misalignment variable model, an exoskeleton model is developed as design references. Then, with the self-aligned mechanism design theory and the multi-DOF joint decoupling methods, the fundamental design ideas and methods of an exoskeleton mechanism which is self-aligned to the human body are provided. Finally, the hip joint is taken as the case study. The hip joint is decoupled into three 1-DOF joints, the hip exoskeleton kinematics is designed, and the coupled human-robot kinetostatic actuation forces are calculated. The calculation results show that the human-robot misalignment interaction forces is controllable with the proposed design scheme. It is theoretically verified that the hip exoskeletons can follow the movements of the human lower limbs and provide the self-adaptive actuation forces for the human body.