Based on the distributed Xin’anjiang model, the model concentration structure was modified by aggregating the small reservoirs within the sub-basin into a virtual reservoir, aiming to study the storage and discharge effect of small reservoirs on the flood process. Taking Dongfanghong Reservoir, a key medium-sized reservoir in Anhui Province, as an example, 14 floods occurred at the beginning, middle and end of flood season during 2014-2017 were simulated by the distributed Xin’anjiang model, which neglected the influence of small reservoirs. It is shown that the model can well simulate relatively large floods in the middle flood season, but not so well for floods in the end of flood season. Taking two flood events occurred in the end of flood season, No. 2015090420 and No. 2017070101, as examples, the distributed Xin’anjiang model considering the influence of small reservoirs was employed to simulate the storage and discharge effects of upper small reservoirs(Wuliyuan and Gaoe reservoirs)on the floods for Dongfanghong Reservoir. According to the comparison, it is found that the results of the Xin’anjiang model with the virtual reservoir in the sub-basin are better than those of the Xin’anjiang model, with the relative error of runoff depth decreased by 23. 2% and 18. 4% respectively, the relative error of flood peak decreased by 52. 2% and 53. 5% respectively, and the Nash efficiency coefficient increased by 0. 92 and 0. 42 respectively.