Abstract: Currently,the RAS algorithm is adopted as the public key algorithm of most existing security systems,which cannot ensure the security of message transmission in digital substation communications.In order to solve this problem,an implementation scheme for authentication mechanisms based on IEC 62351 combined with SM2 cryptosystem is proposed.For situations in which a bus fault occurs in the unified star network,ring network and ring network with redundant loop network in the whole D2-1substation,respectively.The digital signing time for generic object oriented substation/sample value（GOOSE/SMV）messages is calculated quantitatively while the communication delay is obtained through OPNET simulation,and the different maximum transmission delay times of three kinds of network structures with 100 Mbit/s and 10 Mbit/s bandwidths are obtained.Simulation results have proved the effectiveness of the proposed design in meeting the demand of security and real-time in substation communication message.