Abstract: 【Objective】 The objective of the study is to investigate the potential of cotton straw biochar for the adsorption and immobilization of heavy metals Cd²⁺. 【Methods】 Cotton straw biochar (BC500, BC600 and BC700) was prepared from cotton straw, a typical agricultural waste in Xinjiang, at pyrolysis temperatures of 500℃(BC500), 600℃(BC600) and 700℃(BC700), respectively. Meanwhile, experiments of adsorption and passivation were carried out. 【Results】 The results showed that at an initial concentration of 100 mg/L Cd²⁺, the adsorption of Cd²⁺ by BC500, BC600 and BC700 reached 10.47 mg/g, 9.72mg/g and 11.96mg/g, respectively. The pseudo-second order kinetic was the most suitable model for describing the adsorption of Cd²⁺ onto cotton straw biochar. Sequential extraction test results showed that Cd²⁺ was predominantly adsorbed on cotton straw biochar as carbonate-bound fraction (77.74%-82.09%). The exchangeable fraction and unavailable fraction for cotton straw biochar was low (12.14%-14.95% and 5.62%-6.75%, respectively) and the water soluble fraction was negligible (0.15%-0.55%). Compared with the control, applications of cotton straw biochar at different pyrolysis temperatures resulted in an average decrease of 24.29% and 6.52% in the water-soluble and exchangeable fraction of Cd²⁺, respectively, and an average increase of 22.49% and 8.32% in the carbonate-bound and unavailable fractions, respectively. 【Conclusion】 Cotton straw biochar has strong sorption potentials for Cd²⁺ and can be applied to soil remediation to effectively reduce the bioavailability of Cd²⁺.