The upgrading improvement by using augmented capacity conductor could alleviate the insufficient capacity problem of transmission lines. In spite of the significant capacity increase, the maximum temperature of conductors will exceed 80℃, thus it is inappropriate to use the sag calculated in the condition of 40℃, 50℃ or icing without wind to locate towers. The calculation method of location sag when using augmented capacity conductor is analyzed, and the verification according to examples is carried out.