Abstract: Using a mixture of standard sand and kaolin to simulate sandy clay soil,this study investigated the anti-seepage stability of soil improved by microbial-induced calcium carbonate precipitation(MICP). Multi-velocity gradient seepage erosion tests were conducted on standard sand-kaolin mixed soil to monitor changes in soil column height,permeability,and kaolin concentration in MICP-treated soil,and to compare the erosion resistance under different degrees of cementation. The effectiveness of MICP in controlling seepage erosion was evaluated for mixed sandy clay soils with varying cementation levels. Three types of sand-clay mixtures with different cementation degrees were tested; computed tomography(CT)scanning was employed to monitor particle movement throughout the erosion process. The results demonstrate that MICP effectively reduces the migration of clay particles through adsorption,encapsulation by calcium carbonate precipitation,and bridging within the soil skeleton,thereby enhancing erosion resistance. A flow rate of 41.9 mL min^-1 was identified as the critical erosion rate under the experimental conditions. As the degree of MICP cementation increases,the resulting calcium carbonate effectively raises the critical erosion rate of the specimen,with a calcium carbonate content of 6% being sufficient to achieve effective erosion resistance. These findings provide a reference for analyzing the erosion resistance of MICP-reinforced soils.