Abstract: The traditional RMR method is especially focused on constant rating parameters and the form of giving scores.So there is no doubt that it has many indeterminate and subjective factors in the process of rating and cannot get an adequate result under complicated geologic environment.In order to improve the RMR method,this paper puts forward the AHP method to use in rock mass classification.Under this method,the rock mass classification is viewed as a group decision problem.It can readjust the rating parameters based on real geologic environment and calculate parameters' proportion,establish corresponding evaluation criterion.Then it can calculate rock mass total score which is used for the rating.The fuzzy logic theory is used in AHP method to solve fuzzy problem in fact.At last,this new method has been used in the rock mass classification of Dwan tunnel.Compared to the RMR method result for this instance,the classification result of AHP method is closer to the fact.