This paper focuses on the human error evaluation method in civil aviation maintenance based on the Bayesian estimation theory. First of all, taking the maintenance human error probability as a random variables, meanwhile using the airline historical data as a priori information, using the 5% sites provided by the THERP Handbook as the mean probability value of maintenance human error，to determine the prior distribution model of human error using the point estimation method. Secondly, solving estiamtion method for Bayes prior distribution parameters is presented. Finally, the median posterior Beta distribution is taken as ’s Bayesian estimation, to construct the human error probability calculation method for civil aviation maintenance. Through the example analysis on the field data, it shows that as the increase of the number of maintenance, human error probability is closer to the maximum likelihood estimation method of the failure probability. The results of case study shows the, effectiveness, accuracy and practicability of the proposed method in this paper.