Abstract: Through the finite element analysis, it is found that the torsional stiffness of a certain type of loader door can not meet the design objectives. Through using the finite element linear mechanics analysis combined with the sensitivity analysis, the components that have great influence on the overall torsional stiffness of the door can be quickly screened out. This method can shorten the research and development time and improve the production efficiency. The sensitivity analysis shows that there is optimization space in the middle of the door frame and the strengthening plate area of the door lock. According to the engineering experience and mechanics knowledge, the design optimization of problem area is carried out. After optimization, when the load is applied from the top of the lock to the flange of the door, the stiffness increases by 94%; while when the load is applied to the door frame below the lock, the stiffness increases by 148%.