According to the characteristics of distribution automation system, such as wide range of points and wide distribution, a dual protection scheme based on "network layer + application layer" is designed. A password authentication protocol based on the combination of SM2, SM3, SM4 national secret algorithm and message authentication code (MAC) onetime password authentication is proposed to realize twoway authentication and encryption of service data between distribution master station and distribution terminal. Therefore, this protocol ensures the integrity and confidentiality of communication data, solves the problem of network security protection of distribution automation system. Once the multicore heterogeneous independent security chip is applied for hardware acceleration, the speed and efficiency of encryption algorithm will be improved.