The preparation conditions of biochar is described briefly. The main modification methods of biochar,including chemical modification,adding modifying agent method and changing environmental conditions,are discussed. The main advantages of the above modification methods are analyzed. Besides,the adsorption effect of the modified biochar on heavy metals in wastewater are summarized. The experimental results show that the modified biochar has pretty good adsorption effect on the heavy metals in wastewater. The maximum removing rates of heavy metals could reach 99.81%. Furthermore,the adsorption m...