There are demanding requirements for real-time activity and reliability of a communication network for a wide area protection system. Thus a reliability analysis method for a wide area protection communication system based on a dynamic fault tree and a Monte Carlo algorithm is proposed. An extended dynamic fault tree is used to establish the system model, and the sequential Monte Carlo method is used to analyze and calculate the reliability of the system. The reliability and weak links of the system are analyzed by simulation. The results show that the proposed reliability analysis method is simple and applicable. It can quickly find the factors affecting system reliability, facilitate rapid diagnosis and maintenance, and improve the reliability of the whole network. This work is supported by the Natural Science Foundation of Hebei Province (No. F2015502047).