Abstract: The concept "Safety Influencing Range of Freeway Interchange" was defined in this paper.The highway accident distribution was studied by taking 500 m and 100 m as the statistical unit separately in 5 km range on both sides of the interchange, and the result indicates that it is suitable to take 500 m as statistical unit, and based on analyzing and comparing the accident frequency in and outside of 1 km, 2 km, 3 km, 4 km range respectively, the safety influencing range of freeway interchange was confirmed.The theoretical accident percent distribution exhibit was also proposed.The research results can provide important reference for safety analysis and accident prediction model establishment of freeway.