The Badi gully is one of the first-grade tributaries of LancangjiangRiver in YunnanProvince. The authors get the formation mechanism of the debris flow by investigating provenance area, circulate area, and accumulation area based on the field investigation and test analysis in room. This paper brings forward prevention measures that take the monitor and the early warning as the primary measure and the engineering prevention (retaining wall, drainage canal and levee) as the accessorial measure aiming at the characters of the debris flows.