Abstract: Research on the scheme of the vertical landing mechanism of the launch vehicle was done and the design schemes of different landing mechanisms were analyzed and optimized through such methods as graph theory analysis and topology analysis. For a high reliability, the mechanism scheme of a single closed-loop chain was determined. To achieve the goal of a high efficiency, the relevant motion pair selection scheme was determined. Considering the simplification of mechanism energy and other factors, a new design scheme of landing mechanism based on mortise lock was proposed. The research results can provide reference and technical support for the development of the vertical landing mechanism of the reusable launch vehicle.