Thy interpolating short range forecast rainfall value of the National Meteorology Center's T63 and HLAFS,and Wuhan Regional Meteorology Center′s MAPS to the subordinate 7 observatory stations respectively,and using the Grey Prediction Model,24 hours rainfall scale forecast on county level in Xiaogan city in summer was conducted.After the operational application at summer in 1996,it was shown that the quality of general rainfall scale forecast on county level was higher,and the capability of heavy rain area and site forecast was reliable.