Abstract: The traffic safety is closely-related with the physiological and mental characteristics of the drivers. Drivers with different temperament will incline to drive the vehicle in different ways, which will bring about different influence on the traffic safety. It is concluded by the analyses of the average travel speed according to different drivers that: drivers with choleric temperament are full of adventure and drive the most quickly with the high latent occurrence of traffic accident; while the melancholic ones drive lower and more carefully. This paper provides a useful method to the further study on the relationship between the physiological and mental characteristics of the drivers, especially the drivers' temperament, and the traffic safety.