predictive equation was built by using MOS method,after making up the structural characteristic factors which can reflect the mechanism of the synoptic dynamic development of precipitation systems. During research,the HLAFS grid point data of the numerical forecast products by our country is used to formulate the synoptic dynamic development characteristic in Inner Monglia region. The experiment results show that this MOS equation can improve the prediction accuracy,be put into the routine meteorological operation easily and thereby have a good application and popularization value