In recent years, with the occurrence of a series of incidents such as network attacks on Ukraine's power grid, the network security of substations is facing a series of new challenges. At present, there are many kinds of intelligent equipment in a substation, and they face increasingly severe internal cyber threats such as unauthorized access, unauthorized operation and data modification. Therefore, a multi-dimensional network security protection mechanism for substation intelligent equipment is proposed, and the network reinforcement mechanisms such as multi-level identity authentication, distributed authority verification and reverse matrix are introduced to solve the common network attack problems. In order not to affect transmission efficiency and performance, the security, reliability and robustness of network access and control of intelligent equipment are ensured. This work is supported by Science and Technology Project of the Headquarters of State Grid Corporation of China "Research on the Auxiliary System of the Third Generation Intelligent Substation" (No. 520530180015).