The invention discloses a power transmission line tower line system icing early warning system and a method thereof. The system is formed by a power transmission line tower line system finite element analysis module under microtopography and microclimate, a prediction model database module of a power transmission line icing distribution rule and a icing amount based on weather forecast information and a landform characteristic, a static-state and dynamic force bearing characteristic analysis module of a tower line system under different operation conditions, a stress structure state equation database module of the tower line system under an ice wind load, a geographic information system of area where a power transmission line belongs and a central processing system. Data of the power transmission line tower line icing distribution rule and the icing amount based on a regional climate characteristic and a stress structure state equation database of the tower line system are established. Information interaction is performed with data of the geographic information system of the area where the power transmission line belongs so that three-dimensional visualized power grid tower line system ice resistance early warning is realized.