In order to study the electromagnetic environment impact of UHV and UHV AC / DC transmission lines in the same corridor, a simulation model of mixed operation of 500 kV / ± 800 kV AC / DC transmission lines in the corridor is established. The radio interference and audible noise under different weather, pole height and conductor spacing are calculated by using the overhead AC and DC transmission line design module in CDEGS.The calculation results show that: when AC and DC lines operate separately, the electric field distribution is centrosymmetric, while the distribution of AC and DC mixed electric fields has no obvious regularity. Properly increasing the height of pole wire can effectively reduce the intensity of mixed electric field，the audible noise produced by mixed line has exceeded the specified limit value standard, and the audible noise generated by changing the distance between poles and conductors will produce audible noise on hybrid lines and radio interference has little effect. The conclusion can provide reference for the erection of AC and DC lines in the same corridor.