Abstract: In order to understand the effects of tillage systems on soil physical properties of corn field in Northeast China, we conducted a field experiment for four consecutive years under three tillage treatments, i.e.subsoiling tillage (ST), no tillage (NT) and conventional tillage (CT), and analyzed soil physical parameters (soil bulk density, soil three-phase ratio, soil structure index and particle composition).The results showed that, compared with CT, ST significantly reduced the soil bulk density at 0~20 cm soil depth (P < 0.05); while no significant difference existed between the treatments at 20~40 cm soil depth, and NT was with the maximum soil bulk density.ST decreased the proportion of solid phase and significantly increased the proportion of gas phase at 0~40 cm soil depth (P < 0.05), while NT increased the proportion of solid phase but decreased the proportion of liquid phase at 20~40 cm soil depth.ST significantly improved the GSSI(Generalized Soil Structure Index) by 28.3% on average.In addition, the STPSD (Soil Three Phase Structure Distance) value of ST was 15.0, significantly lower than the other two treatments (18.4 and 17.7), indicating that the topsoil physical structure was closer to an ideal state; while no significant difference existed between NT and CT.ST increased the proportion of 0.002~0.2 mm grade particles at 0~40 cm soil depth, in the order of ST > NT > CT.Therefore, ST significantly changes soil structure into an ideal state, with great significance for improving soil fertility and ensuring food security.