The invention discloses an impact shearing device of a rock mass structural plane. The impact shearing device is characterized by comprising a main frame, a normal force pressure device, a shearing box (11) and an impact shearing force infliction device, a horizontal impact channel is arranged on the main frame, the impact shearing force infliction device comprises a teeth-shaped transmission shaft (14) and a gear handle (16), one end of the gear handle (16) is connected with a gear disc (19), and the other end of the gear handle (16) is connected with a gravity disc (17). The teeth-shaped transmission shaft (14) is movably arranged in the horizontal impact channel, the gear disc (19) is supported by rotation of the main frame, and a gear is meshed with gears of the teeth-shaped transmission shaft (14) to enable the teeth-shaped transmission shaft (14) to move in the horizontal impact channel along swinging of the gravity disc (17) to impact and shear a lower-half box. Structural design of the impact shearing device can conveniently achieve impact rock mass with different rates so as to obtain different impact shearing strength.