For balancing excessive concentration of electric power communication network, a optimized method based on Service Importance Balance Based Traffic Routing Assignment Algorithm (SIBTRA) to calculate routing system reliability that has been come up. This method can make sure selection of service routing is feasible, and can provides a theoretical basis about balancing excessive concentration. Firstly, the performance index system for evaluating services was built. A method named Triangular Fuzzy Analytic Hierarchy Process (TFAHP) was used to calculate the values of electric power communication services’ importance level, and then the fuzzy weighted average method was used to compare the degree of importance among all services. Secondly, reasonable service route was chosen by SIBTRA, then the system reliability of electric power communication network was solved by the importance values and the reliability of sites and links. Finally, the calculation method was improved to improve the computing speed and reduce the computational complexity.