This study determined the adsorption of Cd2+ and Pb2+ (100 mg·L−1 of each) in simulated wastewater by biomass xanthates made from starch, chitosan, wheat stalk and corn stalk. The results showed that the adsorption efficiency of Pb2+ and Cd2+ ions followed the order: corn stalk xanthate > wheat stalk xanthate ≥ chitosan xanthate > starch xanthate. The results of kinetic modeling showed that the adsorption process was characterized by physical-chemical adsorption, and that a second-order kinetics equation described the adsorption process well. The optimum conditions for the adsorption of Cd2+ and Pb2+ by corn stalk xanthate were: adsorption time 2 hours, temperature 20–25 °C, and pH 6–8. The results serve as a reference for treating wastewater containing Cd2+ and Pb2+.