In　recent　years,　China＇s　road　speeding　accidents　have　increased　each　year.　As　a　consequence,　the　property　damage　caused　by　the　accidents　is　increasing　as　well.　Since　the　automatic　enforcement　requires　less　police　but　have　good　effect　of　speed　limit　and　have　a　significant　superiority　in　road　traffic　management.　As　a　result,　more　and　more　cities　in　China　use　automatic　enforcement　in　speed　limit　management.　The　paper　analyzes　the　speed　limit　effects　of　two　different　law　enforcement　equipments　namely　the　camera　and　the　radar　separately.　The　research　ultimately　concluded　that　the　radar　has　a　certain　speed　limit　effect　but　the　speed　limit　durability　is　poor.　In　addition,　the　study　examines　that　the　camera＇s　effects　of　speed　limit　are　the　most　effective　as　they　not　only　can　bring　the　speed　down　efficiently　but　also　have　good　continuity　of　speed　limit　effects.　©　2010　ASCE.