The forest fire resulting in transmission lines trip has taken place in recent years, and it has a great impact on the safe operation of transmission lines. According to the long chain structure of transmission line and the situation that network signal couldn’t cover the mountain area, using the characteristics of wireless mesh networks, the embedded technology and the long chain structure of algorithm for low power, a fire early warning and monitor system is proposed based on the feature of forest fire. The communication network includes the terminal, router, centralized device. Besides, experts monitoring software is designed based on B/S architecture and GIS map. After the several months’ operation, application result indicates the developed system can detect the fire with high accuracy and transmit the fire message, providing an effective method for the transmission line fires warning.