Abstract: The silver migration of cards of the digital control system（DCS） in nuclear power plants is viewed as one of the significant causes for the reliability failure of integrated circuit devices. In response to the frequent silver migration and unavailable suppression methods of DCS cards, this paper gives full analysis of the principle of silver migration and the causes of silver migration of DCS cards. Also, the associated suppression methods and mitigation measures on the software and hardware level are put forward and verified by life equation and the highly accelerated temperature and the humidity stress test.As shown by the results, the silver migration can be effectively retarded with the recommended conformal coating, and its failure consequences will be well mitigated by upgrading the software of programmable logic controller. Furthermore, the responses and functions of the card aren’t affected, and its life requirements are met, thereby the safe and stable operation of nuclear power plants is guaranteed.