Abstract: Tunnel construction in karst area will inevitably encounter water inrush disaster.Estimation of water inrush volume is an important basis for emergency rescue and later treatment plan formulation of karst tunnel construction.Sinkhole depression is a special geomorphological unit in karst areas, which is an important channel linking surface water and groundwater in karst areas.The amount of water inrush in tunnels penetrating karst sinkhole is not only controlled by hydrogeology of the karst area, but also influenced by surface runoff recharge of karst sinkhole sub-basin during rainstorm periods.Based on the measured data and statistical data, the formation mechanism of surface confluence flood peak is deduced based on the rainstorm data of small watershed, and a method for estimating water inrush peak value in tunnels penetrating karst sinkhole during rainstorm periods considering the surface runoff recharge is proposed.Combined with the topography, hydrogeology and measured water inrush data of a tunnel site area of Jiguanshan Tunnel, the case analysis calculation and the comparison with measured water inrush are carried out.The results show that the traditional water inrush prediction method cannot consider the influence of underground river and surface water supply, and its prediction results has a large gap with the measured results.This method can accurately predict the water inrush peak value in tunnels penetrating karst sinkhole during rainstorm periods, which provides important support ensuring the safety of tunnel construction and operation in karst areas.