The invention provides a method and a system for determining the galloping intensity grade of a power transmission line. The method comprises the steps of obtaining icing thickness and wind speed datawhich affect the galloping on the basis of a target area; introducing the icing thickness and the wind speed data of the target area into a pre-constructed joint probability density model to obtain agalloping coefficient of the target area; and determining the galloping intensity grade of the target area according to the galloping coefficient. According to the scheme, the method has the advantages that a reference basis can be provided for the drawing of a galloping distribution map of the power transmission line and the galloping early warning and predicting technology, so that the method has not only important academic significance but also very practical engineering application value.