The utility model provides a telescopic air-discharge silencing device of a switching station of the electrical network, belongs to air-discharge silencing devices, and aims at solving the problems that noises caused by an exhaust fan of a 10kV switching station interfere in normal life of residents in the surrounding. The telescopic air-discharge silencing device comprises a hollow housing, a telescopic tube is arranged in a hollow cavity of the housing, the upper end of the telescopic tube is a fixed end that is connected with the housing, the lower end of the telescopic tube is a free end that is telescopic in the vertical direction, the inner wall of the telescopic tube is provided with a silencing layer, the side wall in the upper portion of the housing is provided with an air inlet, a tube hole that matches the telescopic tube is formed in the lower end of the housing, the inner cavity wall of the housing is provided with another silencing layer, the free end of the telescopic tube is provided with an acoustic filtering layer that plugs the air outlet of the telescopic tube, the acoustic filtering layer is provided with multiple silencing chambers and small holes, the small holes penetrate the acoustic filtering layer and are communicated with the silencing chambers, and the telescopic tube is of a horn shape whose diameter is gradually decreased from top to bottom. According to technical scheme of the utility model, most noises are absorbed within the tube wall due to a sound refraction principle, thereby achieving the effect of silencing, namely noise reduction.