Because the natural and geological environment along the south section of Sichuan-Tibet highway( in Tibet) is unique and fragile, debris flow in the area has repeatedly blocked off the mainstream, forming huge dams, and the outburst floods have caused catast rophic damages to the downstream in the recent decades.13 groups of indoor dam-br eak flood model tests were constructed to study the induced flood routing.It is found that the most important factor affecting the discharge of the outburst flood is the developing form of the breach, of which the gravitational initiation causes the largest discharge, followed by hydraulic initiation, and the least one is g radual erosion. The flood discharge and the upstream discharge show the linear relationship approximately . The flood peak occurs when 30% ~ 50% of the reservoir capacity is effused and the time of flood peak in the timeline concent rates on about 1/ 3 of the entire flood duration, no matter what the breach type is. The study can provide a reference to the prediction of debris flow dam-break flood and is beneficial to the comprehensive disaster mitigation in the downstream areas.