Abstract: When the 35 kV distribution line runs parallel to the 750 kV ultra-high voltage(UHV) transmission line in the shared corridor, the power quality such as the three-phase voltage imbalance of the 35 kV distribution line will be affected by the strong electromagnetic induction of the 750 kV UHV transmission line. In order to ensure the reliability of the power supply of 35 kV distribution lines and solve the problem of three-phase voltage imbalance in operation, the three-phase voltage imbalance changes under different distances, heights and different lengths of parallel sections between 750 kV ultra-high voltage transmission lines and 35 kV distribution lines are analyzed. Reliable and feasible solutions based on actual conditions are put forward, including reducing the height of 35 kV distribution lines to the ground while installing shielded ground wires, installing parallel capacitors on 35 kV distribution lines, and installing parallel reactors on 35 kV distribution lines. Through these measures, the impact of the 750 kV ultra-high voltage transmission line on the three-phase voltage imbalance of the distribution line during the operation of the shared corridor can be improved, the ability of the distribution line to withstand the influence of the electromagnetic environment is improved, and the reliability and safety of the operation of the distribution line are enhanced. The technical solutions for the operation design and planning of UHV transmission lines and distribution lines in shared corridors are provided.