Windage yaw disaster is one of the main factors affecting the safe operation of transmission lines, and the monitoring and forewarning system of the windage yew disaster plays an important role in the safe operation of transmission lines. This paper proposes forewarning method of windage yaw disaster based on the minimum air clearance distance, after calculating the windage yaw angle of suspension insulator string and the minimum air clearance distance from the bottom of insulator string to tower body. Considering the influence of micrometeorological factors of windage yaw, four different mathematical models are proposed to predict the windage yaw angle, thus the forewarning is more accurate. Finally, the system platform for windage yaw disaster forecasting and forewarning system is established by C#, and the feasibility and validity of the system are verified by examples.