Abstract: Abstract: Pneumatic subsoiling is a novel subsoiling method based on pneumatic split technology, which injects pressure-air into cultivated soil to form fractures. In order to study the change of soil porosity during pneumatic subsoiling based on Wenner electrical sounding method, a labroatory experiment was conducted in Agricultural Machinery Laboratory of the Engineering Research Center of Northeast Agricultural University from January to April in 2016. Different soil bulk density (1.4, 1.6 and 1.8 g/cm3) and subsoiling pressure (1.4, 1.8 and 2.2 kPa) were designed for the experiment. The initial soil moisture was kept at 18% for all the treatments. At the bottom of the soil bin, a plowpan in depth of 0.2 m was artificially designed by rolling. On the top, a plough layer was of the depth of 0.2 m. The resistivity was measured before and after subsoiling. Then the resistivity was converted into soil porosity by the model established based on a pre-experiment. Then, the porosity increase rate was used to evaluate the change of soil porosity. The results showed that the pressure had an extremely significant influence on soil porosity increase rate (P<0.01) but the bulk density did not significantly affect the results. Thus, the change of soil porosity as affected by pressure was further investigated in soil with bulk density of 1.6 g/cm3. After subsoiling, the soil porosity increased within the horizontal distance of 0.7 m. In the plowpan (0.2-0.35 m), the porosity increase rate increased slowly with the horizontal distance before 0.4 m and reached its peak when the horizontal distance was 0.4 m. The maximum porosity increase rate was 5.1%, 6.0% and 7.5% under the pressure of 1.4, 1.8 and 2.2 Mpa, respectively. After the peak, the porosity increase rate rapidly decreased with the increase of the horizontal distance. The average of the porosity increase rate at the horizontal distance of 0.1-0.4 m was higher than that in the 0.5-0.6 m, indicating small subsoiling effect for the horizontal distance larger than 0.4 m. The porosity increase rate under the air pressure of 1.8 and 2.2 MPa were significantly higher than that with the air pressure of 1.4 MPa (P<0.05). However, there was no significant difference between 1.8 and 2.2 MPa. Considering the effects of subsoiling and energy consumption for subsoiling, we suggested that the subsoiling air pressure was 1.8 MPa when the bulk density was 1.6 g/cm3. The results provides the technical support for development and application of pneumatic subsoiling equipment.