Research conclusions: The research shows that the Cu—Mg alloy contact wire with the 1 20 mm2 cross—section should be used in priority and its tensile force should never be less than 27 kN．The copper alloy with the 120 mm2 cross—section should be used for the messenger wire and its tensile force should be around 23 kN．The span length should be between 55 m and 60 m．The system height can be 1．4 m to 1．6 m．The tensile force of stitch wire should be less than 3．5 kN．The length of stitch wire varies from 1 6 m to 1 8 m．The distance between the suspension point and the 1 st dropper should be around 4．5 m．There should be no gradient on the contact wire．The catenary irregularity of the wave length equal to 2～6 times of dropper spacing should not appear as much as possible.