The present invention discloses a plane braking device for electric winches and electric winch which disposes a section of hollow gear shaft, a section of core shaft, a fixing ring, a wedge shape support, a stopping piece, a braking plate, an elastic element, a wedge shape piece B, a wedge shape piece A, a braking clutch base and so on in a gear box of an electric winch. When a motor works, the section of core shaft of the motor drives the braking clutch base and the wedge shape pieces A, B to rotate, until a gap is formed between the adjacent braking plate and stopping piece between the braking clutch base and the wedge shape piece B, so that the braking effect disappears. When the motor stops suddenly, a heavy load lifted by a tight wire drum provides a reverse pulling force so that the wedge shape piece B produces a reverse thrust force to push the friction planes of the braking plate and the stopping piece, so the plane braking effect is achieved quickly. Based on the plane braking plate, the present invention can increase the braking area and the braking force and achieve safe braking. Furthermore, when there is wear of parts in long usage, so it only needs to replace the braking plate made of friction materials, which can simplify maintenance, reduce the parts costs and ensure service life of the gear box.