objective to build up a systematic mountain road safety enhancement technology, this study analyses severe traffic crashes from 2006 to 2010 occurred on an inter-regional mountain arterial road network in south China. In order to digest these crash data collected from local traffic police stations, the authors conduct the in-depth crash analysis from the aspect of human, vehicle, road, and management. By developing the definition sets for crash deterministic causing factors judging system, the deterministic causes of severe accidents on mountain roads in China are deeply investigated. Results of our analysis indicate that human factor does weigh the most in the occurrence of the severe crashes; main crash types on mountain roads are running-off road, headon collision, overturned; Almost 76% severe crashes occurred on slope/curve combination sites; and freight car shall be given more attentions in reducing the severe accidents.