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Palaeohydrological investigations were carried out in the middle Beiluohe River valley in the middle Yellow River basin. Palaeoflood slackwater deposits (SWDs) are natural records of overbank flooding and are often identified in the Holocene aeolian loess-soil profiles along the river valley. Three bedsets of palaeoflood SWDs were found within the mid-Holocene Climatic Optimum palaeosol (S-0) on the right riverbank. Both the sedimentary and the analytical results, including magnetic susceptibility, grain-size distribution and concentrations of chemical elements, indicate that these palaeoflood SWDs were deposited from the suspended sediment load of overbank flooding. We identified three episodes of extraordinary overbank flooding events. These hydro-climatic events were dated to 7600-7400, 5800-5000 and 4200-4000a BP, from optically stimulated luminescence (OSL) dating and pedostratigraphical correlation. The minimum flood peak discharges were estimated to have been between 12600 and 14100m(3) s(-1) using the slope-area method. These hydro-climatic events are considered to be a regional expression of known climatic events and demonstrate that the mid-Holocene climate was far from stable. These results show that the magnitudes of floods are highly sensitive to climate change in semi-arid and sub-humid regions with a monsoonal climate.