With the development of manufacturing technology and process level, the reliability of DC/DC converter becomes higher and higher, which is a big challenge to the reliability evaluation of DC/DC converter. In this paper, to solve the problem, DC/DC converter is studied by the test of constant electrical stress and temperature ramp stress method (CETRM). With CETRM, time and cost of the test are efficiently reduced. Ten DC/DC converters are tested using CETRM. Failure sensitive parameter, activation energy, failure temperature, failure rate, lifetime and failure rate are acquired, which testifies the application and efficiency of CETRM for DC/DC converter proposed in this paper.