The importance and recent achievements in audible noise control of transmission line are reviewed

and gas corona discharge is referred to the source of audible noise of AC or DC high voltage transmission line.The factors resulting in audible noise of AC or DC high voltage transmission line are analyzed

including the structure

design and construction of the transmission line

as well as the atmosphere and environment.The measures to reduce audible noise of transmission line are summed up

and such engineering solutions to reduce the audible noise as increasing the diameter of bundled conductors

increasing the bundle numbers and changing the interval between bundled conductors are considered applicable.The limits of audible noises of AC and DC transmission lines abroad are introduced.The audible noise limits for Chinese UHVAC and UHVDC projects are listed

e.g.55 dB（A）for UHVAC transmission line

45 dB（A）for UHVDC transmission line in plain

and 45 dB（A）to 50 dB（A）for UHVDC transmission line in high-altitude areas.