The invention discloses a test loop square wave calibration device for a transformer local discharge test, so as to solve the problem that the output waveform is instable when standard square wave calibration is carried out on the test loop. The central position of a bearing disc (5) is provided with an electric hoist (10); an insulated lifting rope (11) on the electric hoist (10) passes through the central hole in the bearing disc (5) and is then connected with a square upper frame plate (16) of a square wave standard rotational station (2); a square lower frame plate (17) is connected in a hanging mode onto the lower ends of four plastic lifting ropes (18) on the lower bottom surface of the square upper frame plate (16); a standard square wave generator (14) is arranged on the square lower frame plate (17); a square wave calibration cable (15) of the standard square wave generator (14) passes through the central hole in the lower frame plate (17) and is then connected with a square wave transmission suction disc (23); and four corners of the lower bottom surface of the square lower frame plate (17) are all provided with contact angle supports (13). A foundation is laid for smoothness and high efficiency of the transformer local discharge test.