We analyzed the compositions and basic properties of agricultural and forest biomass carbon, and used the pot method to study the influence of such element on the remediation of contaminated soils and growth of crops. Results show that agricultural and forest biomass carbon contains various nutrients that are necessary for crop growth, high specific surface area, and pore structure development. Cotton stalk charcoal can reduce bioavailability of Cadmium (Cd) in soil. Under mild Cd pollution, soil treated with cotton stalk charcoal adsorbs Cd at a rapid rate. With increasing extent of Cd pollution, Cd adsorption rate gradually slows down and Cd adsorption amount gradually increases. In soil treated with cotton stalk charcoal, the amount of Cd accumulated in the edible portions and roots of Brassica chinensis significantly decrease. The Cd mass fraction of the edible portions and roots are reduced by 49.43%-68.29%, 64.14%-77.66% respectively. Appropriately adding carbon cotton stalks increases crop biomass. At a certain range, increasing cotton stalk charcoal also promotes the absorption of major nutrients in Brassica chinensis.