This study investigates the impacts of climate change on flood situation in Torogh Dam watershed using a combination of four general circulation models (GCM) of the sixth Phase of Coupled Model Intercomparison Project (CMIP6) under three scenarios: SSP1-2.6, SSP3-7.0, and SSP5-8.5 and semi-distributed hydrological model HEC-HMS over the two future periods of 2021-2040 and 2041-2060. Initially, the performance of general circulation models in the historical period (1993-2012) was evaluated using station data as observational data. In the next step, in order to reduce the uncertainty of the models, an ensemble model was presented using the weighting method MOTP. Furthermore, in order to optimize and validate the hydrological model, six independent flood events in March, April, and May were used and statistical measures of Nash-Sutcliffe Efficiency (NSE), RMSE, and Bias were calculated to evaluate the performance of the model in simulating flood events in the study watershed. The study results show an increase in flood peak and volume in March under all scenarios and in both periods. For April, this includes a decrease in flood peak and volume under SSP3-7.0 in both periods, while under SSP1-2.6 flood peak and volume decreased in the first period and increased in the second period and under SSP5-8.5 increased in the first period and decreased in the second period. Flood peak and volume in May increased under SSP1-2.6 and SSP3-7.0 in the first period, while under SSP5-8.5 in the first period and under all scenarios in the second period decreased.