Abstract: To counter this grave situation of traffic accident which is increased with year in our country, this paper analyses the relationship between the road geometries and the traffic safety according to the fundamentals of the system engineering and the traffic engineering in order to improve the quality of road design and assure safety of traffic, based upon the study about road and environment factor of traffic accident in Chongqing. This paper also puts forward a tentative view which is how to take note of the demand about the dynamic vision and the motion psychology of the driver in the geometries design of road.