Medium and long term load forecasting is important for power system planning and construction. Affected by the New Economy normal and other relevant factors, various regions of China have entered a new period of economic development mode and industrial structure changing. Load structure and load growth pattern, to a certain extent, has changed, which undoubtedly makes the long-term load forecasting more complex and uncertain. To study the models and methods of Medium and long term load forecasting in the market environment is more important. This paper deeply analyzes the new economy normal state's features, refines the factors which can properly characterize the new normal state's changing, and applies them to the medium and long term load forecasting's models; in accordance with the actual data of one province, uses a variety of methods and models to calculate and compare the predictions, and gets the applicability of long-term load forecasting model in new economy normal state.