Abstract: At present, the microbial-induced calcium carbonate (MICP) solidification technology is mainly used in porous sand which is easy to be grouted and connected, but rarely used in low-permeability silt. Based on the results of MICP solidification of sandy soil, using Sporosarcina pasteurii to solidify soft clay, the shear strength index increases obviously with the increase of curing time, the water content decreases greatly during the solidification process and the mechanical properties are improved obviously after solidification, which shows that it is feasible and effective to solidify soft clay by using the MICP technology. In order to understand the solidification mechanism of Sporosarcina pasteurii on the soft clay, the change rules of mineral composition before and after solidification are compared by means of XRD and SEM, and the chemical reaction relationship between Sporosarcina pasteurii and nutrient salts, mineral ions in the soft clay during solidification was determined, and revealed the strengthening mechanism of microbial solidification.