Abstract: In this study using two random variables follows Rayleigh distribution such that X is stress and Y is strength with parameters α and β using different size (n, m). Reliability is estimated using the Bayesian method and Robustfit method of the estimate in samples taken from stress and strength distributions. statistical metrics are used to compare between two methods and to get the best method and from MSE, TD and R2. A small sample of reliability estimates is compared through the Monte Carlo Simulation.