Owing to the advantages of high scalability, powerful bearing capacity and so on, EPON has been successfully applied to the Power Terminal Access Network. According to the bearing capacity characters of the Power Terminal Access Network, the author elaborates the security threat of EPON networking from the information security risks, the system reliability risks and the management risks. According to the security requirements of the Power Terminal Access Network, the author made an exhaustive study about the protection measures of EPON and analyse the influences from the EPON protection measures of electric power communication network to QoS. All the above support for the development of electric power communication network.