In this paper, a preliminary study is carried out on factors affecting the adsorption of heavy metals (Zn2+) by bentonite. It has been found that the quantity of adsorption increases with the increase of adsorption temperature, initial concentration of heavy metal cations, pH value of solution, time of adsorption and speed of stirring, and the decrease of bentonite particulate size. The mechanism of adsorption affected by various factors is also discussed.