The utility model provides a hub reduction structure which comprises a
knuckle shell, a hub, a planetary transmission
assembly, an inner gear ring and a gear ring seat, the
knuckle shell comprises a connecting part and a housing part, and the connecting part is provided with a second step part protruding outwards in the radial direction; a limiting step part is arranged on the side, close to the housing part, in the hub. The planetary transmission
assembly comprises a
planet carrier fixed to the end of the hub, and a mounting groove is formed between the
planet carrier and the limiting step part. The inner gear ring is arranged in the mounting groove, and a first step part which is sunken outwards in the radial direction is arranged on the side, close to the housing part, of the inner ring of the inner gear ring. One side of the gear ring seat is connected with the steering
knuckle shell in a sleeved mode through a spline and abuts against the second step portion through a spacer bush, and the other side of the gear ring seat is arranged in the first step portion, connected with the inner gear ring through a spline and abuts against the step face of the end of the first step portion, so that axial limiting of the gear ring seat is achieved, assembling is easy, parts are saved, and cost is reduced. And the overall reliability is also improved while the cost is reduced.