In order to meet the requirement of high voltage transmission lines monitoring system, this paper presents a heterogeneous integrated network which contains Optical Ethernet, broadband wireless communication networks and wireless sensor networks in high voltage transmission line monitoring system. Moreover, considering the characteristics of the heterogeneous integrated communication network and analyzing the features of service security mechanism in communication network, this paper proposes an authentication and encryption security system, which has certain value in the authentication and encryption aspects to electric power system communication.