As an example， several kinds of phasing arrangements and transposing modes for Jinchang-Jiuquan transmission line are considered， the unbalance degrees of line parameters and bus voltages for 750 kV compact double-circuit overhead transmission lines（CDCOTL） with line tower of T type are analyzed. The influences of different phasing arrangements or transposing modes on the secondary-arc currents and recovery voltages， induced voltages and induced currents are studied. The results show that negative sequence unbalance degrees of bus voltages caused by CDCOTL are relatively low. However， the induced voltages on the de-energized line open at both ends for non-transposed lines are very high， so it's necessary to do the transposition for Jinchang-Jiuquan transmission line. Based on the comparisons and analysis of unbalance degrees of bus voltages， secondary-arc currents， induced voltages for different transposing modes， two kinds of transposing modes are recommended.