This paper summarized the principles and methods that mitigate the debris flow on the basis of risk-reducing ideas. It analyzed the practical problems that the Zhouqu debris flow mitigations have to face, which includes the limited environmental capacity, the difficulties to relocate the town, and the psychology of local people after this catastrophe. Thinking of these practical problems, the authors proposed the comprehensive mitigations which are partial evacuation plus engineering countermeasures plus monitoring and early warning plus education for local resident, and made a relevant detailed explain for each of mitigation measurements.