Rehabilitation engineering and biomechanics are naturally closely related, and biomechanics is the core problem in many rehabilitation projects. In 2021, the latest progress in the field of biomechanics of rehabilitation engineering is mainly reflected in three aspects: biomechanics of anthropomorphic design of rehabilitation equipment and assistive devices, biomechanics of human environment interface, and biomechanics of human-computer dynamic interaction. Based on the latest progress in 2021, this review summarized the research methods, main applications and existing problems of rehabilitation engineering biomechanics, and discussed the future development direction.