The invention discloses an on-line plate edge derusting device which comprises a pedestal; a platform is installed on the pedestal, a tipping seat is installed on the platform, a motor is fixed on the tipping seat, and a wire wheel is fixed on an output shaft of the motor. The tipping seat is hinged on the platform, the tipping seat is provided with a bending plate, and a slot hole is arranged inthe bending plate; and a threaded rod is fixed on the platform, the upper end of the threaded rod is connected with an upper adjusting device after penetrating through the slot hole, and a lower adjusting device is installed on the lower end of the threaded rod, and an upper compression spring and a lower compression spring which are respectively sleeved at the upper and the lower sides of the slot hole are sleeved on the threaded rod. According to the derusting device provided by the invention, the wire wheel is driven by the motor to rotate, so that the on-line plate edge derusting device has high derusting speed and efficiency and a good derusting effect.