This paper deeply studied the performance data of the power transmission network, selected indicators parameter in the characterization of the running state of the network. By analyzing the factors that affect the time series, a trend forecasting algorithm of network performance based on time series decomposition is constructed. It can make quantitative estimation for the future development trend of communication network. The model and algorithm of the paper are verified by the actual performance data. The results show that the forecast value is in good agreement with the actual monitoring data, and it has good practicability, which can provide technical support and judgment basis for the pre-warning of power communication network.