By using clinical data from Central Hospital of Baishan City, Jilin Province and meteorological data， the relationship between colds and weather conditions is analyzed. It indicates that the incidence of colds is closely related with the previous weather changes. A significant weather change process does not correspond with a single high incidence day, but a sustained high incidence stage. The impacts of meteorological environment on the incidence of colds in different population are different. For adults, higher incidence happens when autumn turns into winter and summer turns into autumn; for infants, it happens in midsummer and midwinter due to their poor adaptability to seasonal and weather change and apparent response to cold and hot weather; for children, the feature of incidence is the same as infants in spring and summer, and close to adults in autumn and winter. A discriminant equation to forecast the colds index is established on the basis of correlation analysis between the numbers of colds inpatients among different people and meteorological elements, and proved to have a good prediction level by prediction test.