Abstract: The adsorptions of Pb²⁺ and Cd²⁺ in aqueous solutions by biochar derived from salix, straw and corn stalk at pyrolysis temperature of 500℃ were evaluated. The characteristics of adsorbent were mainly observed by scanning electron microscope (SEM), specific surface area analyzer and Fourier transform infrared spectroscopy (FTIR), and the effects of initial pH, ionic strength of Na⁺ and Ca²⁺ and adsorbent dose in sorption experiments were further investigated. Results show that the alkali and ash content of the 3 biochars were salix straw biochar (SWB) > corn stover biochar (CB) > rice straw biochar (SB), and all the surfaces of the 3 biochars contained large number of oxygen-containing functional groups. The adsorption kinetics and adsorption results indicate that when the pH was set between 3 to 6, the adsorption efficiency of biochar to Pb²⁺ and Cd²⁺ increased with the increase of pH value, and the adsorption efficiency to Pb²⁺ decreased with the increase of ionic strength in the solution. While the adsorption efficiency of SWB on Cd²⁺ increases with increasing ionic strength. In addition, the adsorption kinetic results of SWB, CB and SB to Pb²⁺ and Cd²⁺ met quasi-secondary kinetics, and the correlation coefficient R² was greater than 0.99, indicating that the biochar adsorption rate is mainly determined by the chemical adsorption mechanism. Moreover, the adsorption isotherm model of Pb²⁺ and Cd²⁺ show that the adsorption of Cd²⁺ was suitable to be described by both Langmuir and Freundlich isothermal equation, while the adsorption of Pb²⁺ was only well simulated by the Langmuir isothermal equation, indicating that the adsorption mechanism of Pb²⁺ by biochar was similar to that of monolayer adsorption law, but the adsorption process of Cd²⁺ showed multi-molecular layer adsorption mechanism.