Abstract: 【Objective】 To investigate the effect of biochar on the immobility of cadmium in soil. 【Methods】 Three biochars (B300℃, B400℃ and B600℃)derived from potato straw were prepared. Thereafter, the Cd²⁺ adsorption abilities of these biochars were compared to find the best biochar; the effects of biochar (B400℃) with different amount (0.5%, 1.5%, 3.0%) on the pH, organic carbon and DTPA-Cd content of two typical soils (dark loessial soil and mountain meadow soil) in southern mountainous area of Ningxia were studied by indoor experiment, and pot experiment was also carried out with 3.0% of biochar to study the effects of biochar on maize growth and its uptake of Cd from the dark loessial soil. 【Results】 The order of adsorption capacity of potato straw biochar to Cd²⁺ was: B400℃ > B300℃ > B600℃; the addition of biochar could reduce the content of DTPA-Cd in two typical soils significantly, of which 3.0% was the best, and the decrease of DTPA-Cd content in dark loessial soil was larger than that in mountain meadow soil; the pH value and organic carbon content of the two soils had significant negative correlations with the changes in their respective DTPA-Cd content; the pot experiment result showed that biochar could significantly increase the biomass of maize, and decrease the Cd accumulation in the shoot or root of maize, the 3.0% of biochar could also decrease the transportation of cadmium from root to shoot. 【Conclusion】 The potato straw biochar has obvious immobility effects on cadmium in two typical soils in the southern mountainous areas of Ningxia.