The mechanism of grey model, grey analysis and prediction model of China's energy system are introduced, then the accuracy and variable sensitivity of this model are discussed. The results show that grey energy model has a higher simulating and forecasting accuracies. Along with GDP growth, the final energy consumption in China shows three stages: rapid growth stage, slow growth stage, and slow declining stage. The sustaining period per stage is closely related with GDP growth rate. The longer the used original series is, the larger the future energy consumption is.