Rehabilitation engineering can not only improve life quality of the elder and people with disability, but also reduce burdens of the society and family for care at the same time. With the development of economy and improvement of life quality, rehabilitation engineering will be raised to a new level. Biomechanics provides fundamental basis for the design and assembly of rehabilitation products. As the main reason for rehabilitation is to maximally restore the lost function of body support and exercise, it is important to understand the force transmission and interaction between the body and supporting device. Through biomechanical research, optimized assistive technology for rehabilitation and training program can be designed. This paper will review the major focus on biomechanics research in rehabilitation engineering, including body support interfacial biomechanics, musculoskeletal kinematics and kinetics, finding appropriate control signals, and developing advanced materials, so as to provide theoretical basis for the development of rehabilitation products.