Transmission line as one of the weak links

its safe and stable operation is directly related to the operationof the grid state. Icing is an important factor which poses a threat to the safe operation of transmission lines. To en-hance the icing fault analysis efficiency

icing fault diagnosis model becomes more and more important. In this pa-per

the data of icing tripping of transmission lines in the past five years are analyzed. Based on the influence of mete-orological and micro terrain conditions

a fault diagnosis model of icing fault is constructed

which is based on deci-sion tree. Combing the key diagnostic variable factors and weight coefficients

the calculation method of suspectedfailure probability is proposed. Finally

combining with the diagnosis model

the paper analyzes and calculates theactual running fault cases

and confirms the types of ice faults through manual intervention and on-site investigation

thus laying a good foundation for fault diagnosis and trouble shooting of transmission lines.