Rehabilitation equipment is the most important hardware facilities in recent medical field. The treatment methods led by medical rehabilitation instruments have been widely promoted. Besides, the study of elderlies' hemiplegia rehabilitation has become hot issues. However, the function of rehabilitation instrument on the market is simple. How to carry out design innovation on the rehabilitation equipment has become a difficult problem to be overcome in research. Hence, this paper clearly points out the goal that finish an improved design based on existing rehabilitation equipment, which is study the elderlies' hemiplegia rehabilitation by Contextual Inquiry and observation. According the study, we arranged results of key events and five working models. Then, we did an improved design and got a conclusion by the study results.