In　order　to　study　the　principle　of　the　road　surface　deicing　and　snow-melting　system　where　electric　heating　cable　is　used,　finite　element　method　is　adopted　for　calculating　the　change　of　road　surface　temperature.　The　temperature　distributions　and　changes　of　road　surface　and　inside　are　computed　under　different　environmental　conditions.　By　comparing　the　numerical　results　and　experimental　data,　it　has　been　found　that　simulated　results　are　in　good　agreement　with　those　experimental　data.　The　results　shows　that　based　on　the　analyses　of　weather　data　especially　the　temperatures　in　the　past　ten　years,　that　the　heat　cable　power　range　from　250　to　350　W/m2　per　unit　surface　can　meet　the　requirement　of　deicing　and　melting　snow　for　roads　and　streets　surface　in　Beijing.