The study results of the palaeoflood in the upper reaches of the Hanjiang River suggest that six loess-paleosol sedimentary profiles may record a palaeoflood event in the Eastern Han Dynasty. Four sedimentary profiles (LJZ, TJZ, QFC-B and LWD-A) located in Yunxi-Yunxian section with relatively concentrated distribution are selected as research objects. Based on appropriate terrain data and appropriate hydrological parameters, the HEC-RAS model was used to calculate the water surface line and flood routing simulation in the Eastern Han Dynasty. The results show that the simulated water level of 4 profiles is in good agreement with the estimated water level in the field survey, and the errors are less than 0.25%. The peak propagation time is about 3 h, and the peak discharge is reduced by 1.43%, which is consistent with the flood propagation characteristics in the upper reaches of the Hanjiang River. This suggests that the simulation results based on the HEC-RAS model for palaeoflood events in the Eastern Han Dynasty are relatively reliable. In addition, it also shows that four sedimentary profiles may record a palaeoflood event in the Eastern Han Dynasty. The study has scientific significance for fully understanding the flood evolution law in the upper reaches of the Hanjiang River; it has important practical significance for flood control and flood forecasting in the Hanjiang River Basin.