Cd pollution of soils becomes a global environmental issue, binging in increasing damage to food safety and human health. Biochar can retain metal ions via surface complexation, adsorption, electrostatic interaction etc, and is considered as cost-efficient soil amendment for Cd contamination. However, with the change of environmental factors like pH and water condition, metal ions adsorbed on biochars may be released. In this study, a thiol-modified biochar(T-RSBC) was prepared in order to strengthen the metal retention capacity of rice straw biochar, since the thiol group could form the stable complex with metal ions (like Hg²⁺ and Cd²⁺). And the Cd adsorption capacity of T-RSBC was investigated in the batch experiment and soil reactor experiment. Results indicated that the total S content of T-RSBC was increased from 0.98%(RSBC) to 24.0%, and the content of available thiol group tested by Ellman method was increased to 0.80 mmol/g. In addition, the results of FTIR, SEM-EDS and XPS were also confirmed the successful loading of thiol group onto RSBC. The adsorption of Cd²⁺ ion onto T-RSBC reached equilibrium within 6 hours. In the pH 5 buffer solution system, the saturated adsorption capacity of Cd ion of T-RSBC was 48.1 mg/g, which was 5.7 folds as that of RSBC. After amended into soils, the concentrations of DPTA extracted Cd of soils were significantly decreased to 60.8% - 65.2% in the T-RSBC treatments, which were lower than those in the RSBC treatments (80.0% - 96.3%). In addition, the TCLP extracted Cd of soils were decreased to 82.1% - 86.3% of that in the control treament. The results of Tessier sequential extraction indicated the amendment of T-RSBC decreased the content of carbonate bonding Cd in soils, and increased the contents of Fe-Mn (hydro)oxide bonding- and organic bonding Cd in soils, which lead to the decrease of mobility and bioavailability of Cd. In conclusion, the loading of thiol group onto rice straw biochar increased the interaction between Cd²⁺ ion and biochar, and improved the remediation of Cd pollution of soils. Our study developed a novel thiol-modified rice straw biochar as soil amendment for cadmium pollution, which provided scientific support for the remediation of soil contamination.