The invention relates to a long-term power demand prediction method, which makes the development tendency of the economic society and power demand key indexes of different development stages clear, and adopts a cointegration model to predict long-term power demands. The prediction method comprises the following steps that: firstly, through horizontal comparison, determining the development tendency of the key index, determining the key index which affects power demand growth, carrying out stability checkout on the key index on the basis of Eviews, and ejecting the index which does not meet cointegration checkout; then, carrying out Johansen cointegration checkout, and determining a cointegration relationship to carry out Granger cause and effect checkout; and finally, constructing the cointegration model, predicting the key index, predicting the long-term power demands on the basis of a long-term balance relationship, and judging the future tendency of regionally industrial development. The prediction method provides a new approach for predicting the regionally power demands and judging regional economy and industrial future development, and has a good use value.