As an important part of the spaceborne directional polarization camera, the power supply and distribution system not only needs to meet the functional requirements of converting the primary power provided by the satellite platform into the various secondary power supplies required for the loads, but also needs to meet the requirements of high reliability and long life when the loads are on orbit. The stress analysis procedure is an important method for analyzing the reliability of electronic systems. Based on the stress analysis procedure and according to GJB/Z 299C-2006 "Electronic Equipment Reliability Prediction Manual", the failure rate calculation of the electronic components in the power supply and distribution system of the directional polarization camera is carried out, and the reliability of the power supply and distribution system is analyzed by combining the structural block diagram of the system. The analysis results show that the redundancy design of cold standby can significantly improve the reliability of the system.