Abstract: In view of the deficiency in methods for choosing zonation indicators of mudflow danger degrees,a new method for choosing zonation indicators of mudflow danger degrees is put forward based on the rough set theory in this paper.Firstly,according to the environmental conditions of forming mudflows,an indicator choice system is established.Then the indicators for choice are discretized by indicator grading.Finally,based on the discernable matrix of the rough set,a core set of the indicators is found and the representative indicators are sieved out.The examples show that this method is easy to operate and considers both representativeness and comprehensiveness.