In this paper,first,the concepts of safety state of section and the freeway in mountains are defined and under such definitions,the concept of freeway section in mountains as well as the safety evaluation indexes and standard of the section is put forward. Then,the speed parameters are obtained by installing the traffic information collection equipment near the section requiring evaluation and its upstream. Finally,with real －time speed parameters and historical data of traffic accidents as the evaluation indexes,a safety state evaluation model of freeway section in mountains is established based on the proposed evaluation standard and the probabilistic neural network ( PNN) . Simulated results indicate that the proposed model is capable of evaluating the safety state of freeway section in mountains.