The invention discloses an electric transmission line icing thickness forecasting method for introducing a dynamic de-icing process. The method comprises the following steps that firstly, a pole tower is located; secondly, meteorological data of the place where the pole tower is located are extracted; thirdly, the increasing amount of icing thickness is calculated according to the meteorological data; fourthly, the de-icing thickness is calculated by judging the heat exchange amount of ice and air and heat needed in the de-icing process; fifthly, an icing thickness forecasting value is the increasing amount of the icing thickness minus the de-icing thickness. The pole tower is located, the meteorological data of the place where the pole tower is located are extracted, the increasing amount of the icing thickness and the de-icing thickness are calculated, the icing thickness forecasting value is calculated finally, natural de-icing is fully considered, the difference from actual measurement is small, and the forecasting effect is ideal.