Power transmission line monitoring is a general appellation of automated monitoring and scientific management for power transmission line by advanced techniques, and it’s an important basis for achieving smart grid. Its data transmission system is divided into access network and data network, the access network consists of a variety of terminals, tower nodes and aggregation nodes, which includes on-site and remote networks. The application of flexible and reliable network would guarantee to achieve a high-speed, reliable and transparent data transfer between master station and terminals in the system. According to the data transmission requirements of transmission line condition monitoring system, this paper studies the communication network technologies for access network in the perspective of private and public networks, and after a comparative analysis of these technologies, it proposes a principle of how to select reasonable communication network technologies for different application scenarios.