In order to prevent the risk of relay protection misoperation when single components failure occurring, a method to enhance the reliability of digital substation protection device is put forward. Based on dual processing system hardware architecture, this method used redundancy data check to ensure that signal unknown error will not led to tripping operation. By injecting errors in protection device at experiment environment, verified that this design can effectively prevent the occurrence of false tripping when single fault happened in various key positions. Meanwhile, the practical application results also show that the system can significantly enhance the equipment anti-maloperation ability, reduce the risk of substation malfunction and improve the system reliability and stability.