Abstract: In the scenario of high proportion of new energy, large-scale wind power integration has a more significant impact on the power supply adequacy and supply-demand balance of the power system. Therefore, the power forecasting of wind power has received more attention and research in industry. The accurate mid-long term wind power generation forecasting results can provide an important basis for the grid to formulate the power allocation plan, equipment maintenance plan and mid-long term generation plan after the wind power grid is connected. This paper reviews the current research status of mid-long term wind power generation forecasting from the basic theory, main methods, difficulties and trends. On the basis of clarifying the basic concept, classification and application of electricity forecasting, this paper classifies and summarizes the mid-long term electricity forecasting methods, and analyzes the prediction methods based on historical electricity data, prediction methods based on historical resource reanalysis data, prediction methods considering future resource forecasting data, and combination forecasting method of multi-data. Finally, the main difficulties in the development of mid-long term electricity forecasting technology are summarized, and the possible breakthrough direction in the future is prospected.