Change point reflects a qualitative change in things. It has gained some applications in the field of reliability. In order to estimate the position parameters of the change point, a Bayesian change point model based on masked data and Gibbs sampling was proposed. By filling in missing lifetime data and introducing latent variables, the simple likelihood function is obtained for exponential distribution parallel system under censored data. This paper describes the probability distributions and random generation methods of the missing lifetime variables and latent variables, and obtains the full conditional distributions of the change point position parameters and other unknown parameters. By Gibbs sampling and estimation of unknown parameters, the estimates of the mean, median, and quantile of the parameter posterior distribution are obtained. The specific steps of Gibbs sampling are introduced in detail. The convergence of Gibbs sampling is also diagnosed. Random simulation results show that the estimations are fairly accurate. © 2020, North Atlantic University Union. All rights reserved.