By using muti-variable mean generation function of the predictand and its predictor,the mean generation function is orthogon alized by means of the Gram-Schmidt's method.Meanwhile,the number of mean gene ration function has been selected in the forecast model by means of Couple Score Criterion.Finally,the forecast model of seasonal precipitation of Shanxi prov ince is established.The results indicate that the method is favorable in foreca st of seasonal precipitation of Shanxi province,and is feasible for improving t he accuracy of short-term regional climate forecast.