Abstract: Heavy metal contaminated soil has received increasingly attention in current times, because once entering the environment, detrimental effect could occur to human lives and ecosystems. In order to solve the problem of heavy metal contaminated soil, a series of experiments including toxic leaching, unconfined compressive strength, soil column leaching tests and microscopic testing methods were conducted to study the solidification characteristics of cadmium contaminated soil by acclimatized Sporosarcina pasteurii. The results show that the concentration of Ca2+ and urea had significant effects on cadmium leaching. When there was no Ca2+ and the urea concentration was 0.5 mol/L, the solidified soil had the smallest Cd2+ leaching concentration of 0.42 - 5.64 mg/L. After adding Ca2+, the Cd2+ leaching concentration had a slight increase, and the contaminated soil achieved the best solidification effect when the concentrations of urea and Ca2+ both were 0.5 mol/L, there was no significant change in leaching concentration when urea concentration and Ca2+ concentration continued to increase. When extending the curing time of the solidified soil, the unconfined compressive strength increased, the leaching concentration of Cd2+ decreased, indicating that the increased curing time inhibited the migration of heavy metal cadmium and enhanced the curing effect. As increasing the initial concentration of cadmium in the solidified soil, the unconfined compressive strength decreased and the Cd2+ leaching concentration increased. After adding Ca2+, the MICP reaction was driven forward to produce more calcium carbonate precipitates, making the soil more dense, and the compressive strength of the soil after curing was improved. When the initial concentration of Cd2+ was relatively large, the addition of calcium could improve the curing effect of the soil contaminated by high concentration of cadmium. After permeation of 15 d, the Cd2+ concentration in the effluent for groups adding Ca2+ was smaller than groups with no Ca2+, indicating that the minerals formed by co-precipitation of heavy metal Cd2+ and Ca2+ were relatively more stable. Cd2+ could be better immobilized after a longer period of 28 d curing. After solidification, the weak acid extractable cadmium in the soil was transferred to reducible and residual species, and when adding Ca2+ ions, the proportion of weak acid extractable cadmium decreased a lot. Calcium could enhance the contact of soil particles and improve the soil stability. Scanning electron microscopy (SEM) images show that the soil density in the presence of Ca2+ was higher than that in the absence of Ca2+. Fourier transform infrared spectroscopy (FTIR) results show that CaCO3 precipitated in the soil after solidification. X-ray photoelectron spectroscopy (XPS) analysis show that the amount of CaCO3 precipitation produced in the solidified soil with Ca2+ was more than that without Ca2+.