Abstract:Abstract : Research purposes : The extrance and exit sections of tunnels constructed in southwestern are always located in valley. The terrain cutting is intense and the rockfall disasters are common at the heading slope. To evaluate the rockfal l risk,flow chart of extension assessment of rockfall risk was established and multi - index extensive comprehensive evaluation model was firstly built and then used to determine factor weight for avoiding human subjective effect,to provide the basis of rockfall hazard management,rockfall calculation and prevention project. Research conclusions:( 1) The extension theory was used in the rockfall risk evaluation. Furthermore,flow chart of extension assessment of rockfall risk was established and multi - index extensive comprehensive evaluation model was built. (2) Some main influencing factors witli non - dimension were preprocessed and a simple correlation functions was proposed to make evaluation index comparable. (3) Rockfall risk was classified into very low risk, low risk, medium risk, high risk and very high risk. The result was validated using a case study and compared to the result got from AHP - Fuzzy mathematics model,which shows the evaluation model is feasible. (4) The results of this paper can provide a newmethod for rockfall risk evaluation.