In the progress of the trial run of liquid rocket engine, the situation of zero-failure data may happen. For zero-failure data, the reliability of the liquid rocket engine was assessed by the least square method with the classical estimation and the Bayes estimation based on the analysis of the life distributing. An analysis of the estimate result was also given. The computational results indicate that the least square method combined with the Bayes estimation is suitable for the reliability analysis of liquid rocket engine in the case of zero-failure data.