Abstract: The carbonation method of reactive MgO-stabilized soils is an innovative technology for the treatment of soft soils with low carbon. The products produced by carbonation reaction can effectively reduce the porosity of solidified soils. Based on the existing researches, the permeability of reactive magnesia (MgO)-carbonated soils is highlighted for its application in engineering. Through the laboratory permeability tests, the influences of reactive MgO content, carbonation time, initial water content and CO₂ ventilation pressure on the permeability coefficient of carbonated silt and carbonated silty clay are systematically studied. In addition, the permeability coefficients of Portland cement (PC)-treated soils is used for comparison under the same conditions of curing agent content and initial water content. The investigation results indicate that the permeability coefficient of reactive MgO-carbonated soils reduces with the increasing MgO content, and it is in the same order of magnitude compared with PC-treated soils with the same curing agent content. The permeability coefficient of carbonated silt is obviously larger than that of carbonated silty clay. When both the reactive MgO-stabilized silt and silty clay are carbonated for 6.0 hours, the corresponding permeability coefficient can reach the minimum (10^-6). The ventilation pressure has little effect on the permeability coefficient of reactive MgO-carbonated soils, and the permeability coefficient is slightly smaller when the ventilation pressure is 200 kPa. Therefore, the reactive MgO-carbonated soil has a similar impermeability to the cement-treated one, and has a good prospect of popularization and application.