The economy and construction of cities/towns in the mountain areas will grow rapidly along with deepening of the western development program, during which debris flow disaster will be more serious. How to solve this problem and mitigate the debris flow disaster is an important task. In this paper, the distribution, harm and developing tendency of debris flow were analyzed. After discussing prevention projects, rebuilding and expanding of old cities/towns and traffic construction that will meet debris flow problem, integrative mitigation countermeasures, such as controlling debris flow by civil engineering, improving drainage area environment by biologic project, forecast of risk zones and disaster situation, were put forward. The economy and construction of cities / towns in the mountain areas will grow rapidly along with deepening of the western development program, during which debris flow disaster will be more serious. How to solve this problem and mitigate the debris flow disaster is an important task. In this paper, the distribution, harm and developing tendency of debris flow were analyzed. After discussing prevention projects, rebuilding and expanding of old cities / towns and traffic construction that will meet debris flow problem, integrative mitigation countermeasures, such as controlling debris flow by civil engineering, improving drainage area environment by biologic project, forecast of risk zones and disaster situation, were put forward.