When the landing gear is locked, the lock hook and the lock ring should ensure a certain gap for safety. Aiming at the reliability problem of motion accuracy in the process of landing gear setting up, the reliability evaluation model of locking accuracy of upper lock was established by taking the clearance on the upper lock as the research object. In order to study the reliability of the accuracy of the upper lock the absence of data, the prior distribution was combined with the test data to obtain a more reasonable parameter distribution, and a Bayesian update iterative model of upper lock accuracy was obtained. It can be extend the information of the analysis data and improve its accuracy, which provides more effective information for the subsequent reliability evaluation of upper lock.