Orthoses and auxiliaries are important to the people with lower limb disabled in their daily lives. The purpose of this study is to survey and discuss the existing walking auxiliary mechanism for the lower limb disabled people, and to design a new walking auxiliary mechanism to improve their walking gesture. In order to develop a new auxiliary mechanism for the people with lower limb disabled, commercial orthoses and patents are colleted, analyzed, classified, and compared to each others. Several interviews with a lower limb disablement are arranged and understand what they need. After integrating all the collected information as the design input, theories of mechanism structure synthesis, dimension synthesis, mechanism analysis are utilized to develop a mechanism design of auxiliary for lower limb disabled people to walk, to go up and down the stair. The Pro-Engineering, a CAD software, is used for solid modeling and the Visual Nastran, a CAE software, is applied for motion simulation. The results of computer simulations of walking and climbing up stairs are compared to that of video taken from the interviewed people.