In recent years, with the increasing proportion of distributed power supply, electric vehicles and smart appliances accessing to the user side, the demand side resources that can be mobilized are more and more abundant. The impact of multiple variables on demand side response is explored, a multi-order grey prediction model based on grey correlation degree and a prediction method combining Markov chain fuzzy matrix are proposed to predict long-term demand side response ability. The multi-order grey forecasting model adopted mainly takes into account the time-space characteristics of load independent variables and the correlation of multiple external variables. When the state variables and time variables are discrete data, Markov chain has a good effect on adjusting the errors in the process of accumulating grey theory.Therefore, Markov chain fuzzy matrix is used to correct the prediction errors, and improves the prediction accuracy of long-term demand side response ability.Combining with the load data of Shanghai in recent 10 years, the validity of the forecasting method is verified.