Abstract: In this paper, a nonsteady atmosphere-earth surface coupled anomaly model is used to carry out diagnostic and prediction experiments of droughts and floods in summer for 24 monthly cases. The results show that this dynamic and statistical externally combined MOS method is convenient and easy to use for the prediction of droughts and floods and is of certain forecasting accuracy and hence is easily applicable for operational short-range climate forecasting. This method is of the potentiality for further developing and improving.