Abstract: The traffic situation, traffic accident features, accident types and accident influencing factors in mountainous roads in Yunnan province are analyzed. The mechanism for traffic accidents is studied. The causes for traffic accidents in black-spot on mountainous roads in Yunnan are discussed from the aspects of human, vehicles, roads and environment, and countermeasures are presented. Analysis shows that the low level of road conditions, people's quality of safety, vehicle performance and safety management in mountainous areas of Yunnan is the fundamental cause of major accidents. Therefore, mutual match of the systematic elements should be ensured to improve system safety, maximize system functions and achieve intrinsic safety.