With the introduction of market competition, the enterprise competition and the efficiency of resource will be improved. Accurate monthly load forecasting can improve power system economic benefit and social benefit, and the error of load forecasting risk directly affects the safety and stability of power supply. This paper established the short-term load forecasting exponential smoothing model based on the seasonal variation and seasonal ratio theory, and predict the raw load forecast data. For Mongolian East network to carry out analysis, the results show that the proposed method is reasonable and feasible.