A three-stage subsoil interval mixing four-gang plough (TSIMF) was created to ameliorate the condition of the planosol soil. To obtain wider working width (2 m), the previously designed three-stage subsoil interval mixing plow (TSIM) (working width = 1 m) was doubled and unified. The soil penetration resistance was measured before and after the tillage operation of the TSIMF to contrast the tilling effect. The predicted draughts and the predicted draught moments were also calculated and compared for the previous and present prototypes: Three-stage Subsoil Mixing Plow (TSM), Three-stage Subsoil Interval Mixing Plow (TSIM), and TSIMF. The predicted total draught and the minimal predicted draught moment of the TSIMF were discussed to find out the proper working traction which could keep the tractor running straight and making it proceed ahead with balance. The results showed that the soil penetration resistance was reduced obviously after the tillage of the TSIMF. The predicted total draught of the TSIMF will be about 90 kN including the running resistance of the tractor. The predicted draught moment of the TSIMF will be the smallest of three multi-stage mixing plows at -10 kNm when the tractor width is 2 m.