The low temperature biomass carbon modified by KOH(BC-P),high temperature biomass carbon modified by KOH(HC-P),low temperature biomass carbon modified by NaHS(BC-S)and high temperature biomass carbon modified by NaHS(HC-S)are prepared respectively. The influence of solution pH,adsorbents dosage,temperature and initial concentration of Hg2+on the adsorption of Hg2+of the four modified adsorbents are discussed. The results show that the adsorption capacity of BC-S is better than the other adsorbents. The maximum adsorption amounts is 8.48 mg/g and the removal percentage is 97.89% at the condition of pH 4,dosage 1.2 g/L and temperature 298 K.The pseudo-second-order model can describe the adsorption kinetic of BC-S on Hg2+well and the adsorption behavior follows Langmuir model. Adsorption thermodynamics show that 298 K is the most favorable temperature to adsorb Hg2+.