With the growing demand for electricity from all industries, the scale of China's power grid is also rising. The historical data of online operation of the power grid has increased explosively, and it is a great challenge to effectively utilize the historical data to achieve stable assessment of the online operation status of the power grid system in the context of big energy data. In the context of big energy data, this paper realizes automatic mining of grid dispatch operation characteristics and rules by using data mining methods and establishing association analysis models, and finally uses five months of online historical data from a provincial dispatch center for offline analysis. Based on the discovered grid operation rules, it is shown that the model established in this paper can improve the online analysis of the grid, and the effectiveness of the proposed method is verified.