Abstract: The expressways which were built at the end of the 1980's and the beginning of 1990's exist some design deficiency due to the absence of national technical standard at that time,and this leads to safety hidden trouble.At the same time,almost all the expressways exist problems like volume over load,too many crash accidents.So,broadening is a good chance to improve.The paper analyzes the design factors which influence the traffic safety and evaluates the current Chinese design specification on median,shoulder,roadside,curb and the ramp's length of the interchange.Some suggestions which may be useful to improve the road safety are also put forward.