Reliability plays an important role in power electronic systems by which the number of system failures, repair costs, guarantee and etc are estimated. In this paper first, a boost power factor correction (PFC) converter is simulated in discontinues conduction mode (DCM) and continuous conduction mode (CCM) under different output power ratings. For these simulations, all of the inherent parameters of MOSFET and diodes are applied according to the actual types. Then, reliability calculation is done based on MIL-HDBK-217 standard. Results have shown that the boost PFC converter would have better performance from reliability point of view in CCM operating mode.