Conductor galloping on the transmission line will cause serious security threat and economic losses of power grid. In order to alert galloping accidents, a graded early-warning scheme of transmission line galloping based on grey clustering analysis is proposed. According to keys of galloping, an indicator system determining the probability of galloping is established. There are three aspects, including meteorological factors, wind incentives, and line properties. The analytic hierarchy process is utilized to calculate the weight of indicators, and the whitening weight function is adopted to calculate the probability of galloping represented by each indicator. Thus, a graded early-warning scheme can be designed by grey clustering analysis. The calculation result of the example is consistent with the actual galloping state. The early-warning system of this paper can provide reference for the prevention and control of galloping in reality.