Thee invention discloses a calculating method for predicting ice-coating power transmission conductor tension. According to the method, first, historical data of the ice-coating power transmission conductor tension are utilized to construct a difference time sequence, then, an autoregression measurement model is set up on the difference time sequence, a smallest information criterion is utilized to estimate a model order number p, the Yule-Walk method is used to estimate model parameters, and finally a predicted value of the ice-coating power transmission conductor tension in a plurality hours in the future is calculated. The method can be used to predict dynamic conditions of the ice-coating power transmission conductor tension, has the advantages of being strong in real-timeness and high in precision, and effectively solves the difficult problem of prediction of the ice-coating power transmission conductor tension.