Abstract: Based on the condition that the performance test data of liquid rocket engine is subject to normal distribution with constant standard deviation, the Bayes method is used to analyze the environment factor of ground and space performance test. First, according to the history test data and expert's information, the prior distribution of environment factor is presented. Then, combined with limited space test data, the Bayes formula is used to calculate the environment factor. Finally,the method for performance reliability analysis under space test environment is presented. An example is given to illustrate the validity of this method.