The characteristics of High Voltage Direct Current(HVDC) power supply are studied, as well as the radiation sensitive parameters. The on-line irradiation examination method is designed. The irradiation examination system of HVDC is developed for parameter test on dose rate, total dose and neutron radiation. The validation test is performed by using HVDC SWM012RH in the examination system. The test results indicate that the examination system can be used to test most parameters, and the test precision meets the requirement of 1%. This work has laid a foundation for HVDC devices radiation examination validation and radiation hardening evaluation.