Currently there′s only engineering approach available on the landing gear efficiency calculation, this approach can only do rough analysis. In this paper, based on a typical three dimensional landing gear operation mechanism, by using the Lagrange equation of the second kind and Matlab programming language, the efficiency and it′s influencing factors has been analyzed. The results confirm that the efficiency is sensitive to the geometric parameters which is directly related to the actuator. The analysis result could be helpful for the optimization of landing gear.