Load forecasting is one of the basic issues of the electric power industry. However, because load has a certain social attributes, the improvement of the accuracy of load forecasting result is a difficult issue. This paper first used k-means cluster method to find similar data from historical date and weather data, and then used support vector machine (SVM) for forecasting. Seen from the result, the proposed method's MAPE is 0.88%, but BP-ANN and ARMA are 1.66% and 3.81% respectively. It is proved that this method has a high accuracy.