In order to avoid the complex forecasting model of mid-long term power load by traditional methods, the research of mid-long term power load based on BP network and RBF network is done according to the past power load data. Two networks can obtain lots of factors from training samples automatically which influence power load. The ability of two networks for forecasting is compared with the training speed and forecasting errors. Two networks have a good performance in forecasting the power load verified by the simulation results and the measured values.