The invention relates to an optimal selecting method of real-time correction models in a flood forecast system, which belongs to the technical field of flood forecast. The optimal selecting method comprises the following steps of: firstly, configuring at least two existing real-time correction models and selecting a precision evaluating indicator for the flood forecast system; extracting a time period just before the forecast time of the flood forecast system as an attempting forecast time period after system initialization; respectively applying the real-time correction models to the attempting forecast time period for attempting real-time correction forecast so as to obtain attempting real-time correction forecast runoffs; respectively counting the precision evaluating indicators of theattempting real-time correction forecast runoffs, and selecting the real-time correction model corresponding to the attempting real-time correction forecast runoff with the optimal precision evaluating indicator as the optimal real-time correction model. The optimal selecting method adopts multiple kinds of the existing real-time correction models for multiple times of attempting real-time correction forecasts so as to select the optimal real-time correction model applicable to floods in the current valley in the flood forecast system, and thus, the precision of the flood forecast system in actual forecasts is increased.