Zhaohegou is one of well known debris flow disastrous gullies in Chengxian County. There are 390.78×10⁴m³ loosed solid materials in the gully with very favorable formation conditions for debris flows. In order to protect the farmland, the villages, the roads and Huangzhu city in the upper reach of Dong River, based on the formation mechanism, the developmental mechanism and the features of debris flows in Zhaohegou, this paper analyzes the seriousness of the debris flow disaster and the necessity of its prevention. A comprehensive controlling program is put forward, taking the blocking as the dominant measure,and combining the comprehensive treatments of the debris flow silting ground, the draining channel and the barrage. After the project is completed, the comprehensive benefits will be produced every year. Now the debris flow has been changed into a usual flood flow. Its threat to Dangchang town has been eliminated. The operation of the project is analyzed to reveal its engineering deficiencies. Considering the characteristics of the debris flow; the project is evaluated, focusing on the design of the control projects, the advantages of these projects and the optimizing methods. This analysis provides some guidelines for the prevention and control against debris flow.