With the development of The Times, people are faced with a variety of pollution crises, especially the heavy metal pollution to the environment. As a common heavy metal pollution ion in water, how to effectively remove Hg2+ has become a big problem. In view of the above problems, ZnCl2 modified peanut shell was applied to adsorb Hg2+. By studying the influence of different adsorption conditions on the adsorption rate and adsorption capacity of Hg2+ after ZnCl2 modified peanut shell, the best adsorption conditions were explored, and the dynamics, thermodynamics and isotherm properties of the adsorption process were explored. The kinetic adsorption isotherm and thermodynamic experiments showed that the adsorption process of Hg2+ in peanut shell is more in line with the quasi-second order kinetic equation and the Freundlich adsorption isotherm, and it was a spontaneous exothermic reaction and entropy reduction. The X-ray diffraction and scanning electronic microscopic images, indicated a good adsorption capacity of the sample. The above results can conclude that the ZnCl2 modified peanut shell can effectively adsorb Hg2+, and the reaction conditions are mild and high adsorption efficiency, which can be used as a new adsorption material for heavy metal pollution.