The invention discloses a refined covering ice model establishment method for a power transmission line. The method includes the following steps of extracting the hour average temperature, the relative humidity, the rainfall, the wind speed and the temperature and humidity vertical profile data of the pole and tower point of the power transmission line, judging whether the type of the covering ice stage at the current time is a covering ice increase stage or a covering ice falling stage or a covering ice keeping stage according to meteorological elements, and calculating the covering ice weight, the covering ice wire diameter and the standard ice thickness according to different covering ice stages. The method has the advantages that refined and reliable analysis products of multiple key meteorological element products of the power transmission line can be provided; differentiated covering rice thickness estimation products in the area are given; when the method is applied to the manual line patrol arrangement plan of the power transmission line, the plan is intensive, the operation and maintenance cost is reduced, and the line operation and maintenance efficiency is improved; a more reasonable power transmission line covering ice thickness planning scheme is provided, and economic benefits are improved through the combination with the line construction cost.