Abstract: In accordance with the features of hydraulic pump, this paper analyzes the failure mode and selects the sensitive stress. According to failure effects that sensitive stresses impose to hydraulic pump and researches that the U.S.A life test standardization develop, we can drive at the conclusion that the synthetic stresses reliability test can verify the reliability and the life of hydraulic pump. Because hydraulic pump has many characteristics such as high price, long life and small test samples, this paper also analyzes the statistical method for synthetic stresses life test under variable load spectrum. The life test experiments indicate that the method of synthetic stresses life test are satisfied to analyze the life of mechanical-electrical products.