In order to reduce the influence of wing box deformation on the spoiler control surface of an aircraft, a linkage mechanism was adopted for the suspension at both ends of the spoiler. During the stiffness characteristic test, it was found that the monitoring data of the spoiler structure showed a jumping trend which was not consistent with the conventional rudder surface test and the theoretical expectation. In order to solve this problem, the fish-bone method was used to analyze the experimental phenomenon. After the problem was located quickly and accurately, the structure were re-analyzed by the nonlinear analysis method of geometric large deformation based on Patran/Nastran platform. A numerical calculation curve which is in good agreement with the experimental phenomenon is obtained. The factors affecting the support stiffness and the solution to the problem of large deformation of the structure are discussed.The analysis method provides a solution for the dynamic problems of flexible mechanism, and the numerical results and the discussion have guiding and reference value for the design improvement. The cause localization analysis process of the test phenomenon can provide reference for other experiments.