In order to solve the problems of high cost, communication delay and long dynamic adjustment calculation time in the existing transmission line monitoring, an overhead transmission line monitoring system based on the Internet of Things (IoT) is proposed. A transmission line communication model considering wide area and non-wide area communication and a transmission line channel model based on roentgen attenuation are established; a nonlinear integer programming optimization model of the overhead transmission line is established by considering communication service quality such as successful transmission rate, delay, robustness and the like; and a suboptimal solution finding algorithm is proposed, and an optimal solution is calculated in near real time according to the change of the channel quality between transmission towers in a network graph. In the experimental stage, compared with the optimization method, the computing time of the proposed model is better than that of the path decision algorithms such as A * and genetic algorithm, which is 10 times and 2.25 times shorter, respectively. The results show that the proposed system provides important data support for dynamic thermal rating, real-time structure sensing and accurate fault location of overhead transmission lines during continuous monitoring.