Conductor ice and ice shedding have harmful effects on the safety operation of transmission line, so real-time estimating the dynamic process of icing-growth and icing-shedding for transmission line is important for operation and maintenance decision. On the basis of influence factors analysis of ice growth and ice shedding, this paper proposes a multi-time scale estimation model of dynamic process of ice growth and ice shedding for transmission line based on the micrometeorological monitoring data. The monitoring records of a transmission line of Xinjiang power grid are taken as example for model establishing, the comparison of the test example and the real operation results and other methods indicate that the proposed method can well estimate the dynamic process of ice growth and ice shedding for transmission line. It is very practical and can be applied to the monitoring and warning systems of ice growth and ice shedding, which provides guide to the power system operation dispatching and transmission line maintenance decision. This work is supported by National Natural Science Foundation of China (No. 51707018), China Postdoctoral Science Foundation (No. 2017M612907), and Science and Technology Project of State Grid Xinjiang Electric Power Co., Ltd. (No. 5230DK16001P).