Abstract: Effectiveness post-evaluation of prevention engineering is an important link in debris flow control. It can be used in inspecting prevention engineering quality, discrimination of formation mechanism. It also can provide reference to debris flow prevention and control in the future. This paper refers to post-evaluation theory on construction projects and combines with many examples of debris flow control projects. Three primary indicators and ten secondary indices are selected to build effectiveness post-evaluation indices system of debris flow control. The three primary indicators include control effectiveness, beneficial result and rationality of control scheme. The ten secondary indices include change of topography, control of solid matter and effectiveness of guide control engineering, economic benefit mobilization of environmental benefit, social benefit, recognition of debris flow mechanism, parameters security, coordination among each control engineering and difficulty of implementation process. Then, effectiveness post-evaluation model of debris flow control project is established on the basis of fuzzy comprehensive evaluation and analytic hierarchy process. At last, the model is applied to the verification and analysis of Dashuigou debris flow control project in Lintong, Xi'an.It concludes that the effectiveness of this model is fine and has the certain promotion application value.