Abstract: Effects of road, traffic, facilities and environment on road traffic safety were investigated for improving road safety and eliminating traffic black spots. On the basis of analysis cause identification methods about black spots, including fuzzy clustering, gray correlation analysis, and rough set, and its suitability, taking G104 line K2177—K2178 section for example, and screening disadvantages in road traffic, it was found that the main factor of black spot was the interfering of surrounding environment and the secondary factor is the lack of lighting facilities, and traffic infrastructures were taken to improve it. The results showed that: Fuzzy clustering was applied to handle black spots which had large accidents data, and gray correlation analysis method could be applied to deal with black spots of which the major factors had been determined, and rough set could be used to identify the causes of black spots with imperfect information.