Climate change is one of the most important challenges that will affect different parts of human life on Earth. The warmer climate conditions will aggravate the water cycle, also will cause changes in rainfall, and amount of runoff and its occurrence time. One of the effects of this phenomenon is its effect on extreme events in the river flow regime, which has been studied fewer in Iran. One of the most important hydrological parameters affecting the status of aquatic ecosystems, hydroelectric power generation, reservoir management and industry is low flow regime. Flood flow can also affect the bottom areas of the basin and cause irreparable damage. Hence, it is necessary to consider changes in these parameters in future periods under climate change conditions. In this regard, this study has examined the Zayandeh-Rud River regime in the future under the influence of the phenomenon of climate change. For this purpose, 27 weather stations and 3 hydrometric stations were considered in order to examine the effects of climate change on the flow regime in the near future periods (2020-2049) and the far future (2070-2099). Given that general circulation models (GCMs) are considered as important sources of uncertainty in climate change impacts, their temperature and precipitation variables used from 26 GCM models under RCP2.6, RCP4.5 and RCP8.5 retrieved from IPCC fifth report. After the spatial downscaling GCM data for the meteorological studied stations, these data were imported to the LARS-WG weather generator along with observational data, for the temporal downscaling and production of climatic data. Then, based on the base period (1971-2000) and the evaluation period (2005-2001), the GCM models, which had the most adaptation to each of the climatic variables (temperature and precipitation) at each station, were selected. Future weather data were generated by selected models for each climate variable at each station using the LARS-WG weather generator and the published emission scenarios for the near future period (2020-2020) and the far future period (2099-2070). These data were imported into SWAT hydrologic model to simulate daily flow in the future periods. The SWAT model after calibrating, and validating using observation flow, simulated daily flows in future periods at each hydrometric station using downscaled temperature and precipitation scenarios. The daily flow data flow was used to study extreme flow regimes during the observation period (1995-1999) and both near future (2020-2049) and the far future (2070-2099). The results of this study indicate that it was observed that all three types of flow regime (minimum, average and maximum) in the future will increase in the future and this increase for the near future will be far away from the future period. It will be tighter. For the maximum flow, in addition to changes in the flow rate, the number of flood events will also increase and this number will be far away from the future period for the near future. On the other hand, the amount of minimum flow and natural stream of the river will increase in the future, but due to the increase in water harvesting and political, social, economic and environmental issues, this amount will not meet the needs of the region and the need for planning for management Water resources are felt in the basin. Keywords: Climate change, Zayandeh-Rud watershed, River flow regime, Downscaling, General circulation models, SWAT hydrologic model, LARS-WG weather generator.