The aircraft in the flight test phase, the technical status will change with the progress of test，at the same time it existes the few fault sample, this has a great impact on the reliability assessment results of aircraft. In view of the above problems, firstly,Bayesian data Fusion and Monte Carlo method were used in combination to solve the problem by modeling, finally to give the complete status of aircraft reliability results. This is of great significance for the subsequent flight test reliability assessment.