Abstract: In the case of the condition of finite test data, in order to solve the problem of reliability prediction for a certain type of laser range finders, which are produced on a small scale and complicated, reliability models are established with analyses of the operating modes of the rangefinders. On the basis of the test data from the previous similar products, reliability of the system is predicted with the method of similar circuit. According to the life of laser crystal, dye piece,totally reflecting mirror, light focusing cavity and so on, laser life is predicted.These predicting values are verified in actual use. This serves the function of reference in system design and application.