Icing on transmission line is relevant to weather condition and conductor temperature.At present

the correlation analysis of the weather parameters and wire icing is not comprehensive and systematic

and in some studies the impact of conductor temperature on transmission line has not been considered

therefore the main factors influencing wire icing have not yet been determined.This paper collects the monitoring data of icing from the 220 kV Tongli power lines and 220 kV Jiyangerhui power lines

analyzes the relation among transmission line icing

conductor temperature and local meteorological conditions

such as ambient temperature

relative humidity

wind speed

etc.by making use of grey relational analysis method

and achieves the correlation degrees between icing and these four factors respectively to determine the key factor influencing wire icing on the two transmission lines.Results show that the correlation analysis result of the 220 kV Tongli power lines is consistent with the one of 220 kV Jiyangerhui power lines

and the correlation degree between transmission line icing and each influencing factor is similar one another.The importance sequence of the four factors influencing transmission line icing is ambient windspeed > conductor temperature > ambient temperature > ambient relative humidity

which indicates that the ambient windspeed is the key factor influencing transmission line icing.