The transmission line’s equivalent ice covered thickness has an important significance to the defense against the ice storm, but no accurate method can measure equivalent ice covered thickness of the conduct on the spot, in order to obtain the ice covered thickness of the conduct during the severe ice coating period and give suggestions for decision-maker. A method for ice covered thickness measurement which based on the secondary development of electronic total station is presented, the sag has a force relationship with its vertical loads, besides the sag can be easily and quickly measured by electronic total station, then the ice covered thickness can be calculated. Choose the smart electronic total station which equipped with Windows CE operating system, the users can combine the sag measurement and ice covered thickness measurement and program a unique instrument-end application, so the ice covered thickness can be measured by the electronic total station, this method was proved through the real measurement.