By a study of the six-phase transmission line advantages in construction cost and environmental characteristics in comparison with the double-circuit transmission line，the reduction in the construction cost and space of the transmission corridors are quantitatively validated through the calculation of the space between towers.The natural power transfer capacity of six-phase transmission line is calculated.It is proved that six-phase transmission line is more economical as it can increase the natural power transfer capacity while reducing the installation costs.With respect to environmental characteristics，an account is given of the lower audible noise and radio interference field in six-phase transmission lines than in the double-circuit transmission lines by proceeding from an analysis of the maximum electrical gradient of the conductor surface.