Icing may causes conductor galloping,and ice-shedding nonuniformly may lead to conductor jumping.Heavily icing can even cause pole leaning,collapse and conductor breaking etc.This paper introduces the icing reasons of overhead transmission lines. Anti-icing and de-icing measures in China at present are expounded in detail.The measures can be classified as two kinds:one is ice-melting by exterior heating of the overhead line,the other is mechanical stripping ice from conductors by equipments.Through the comparison of these methods,this paper supplies references for anti-icing,de-icing and security of overhead transmission lines.