Using diatomite, chitosan and Fe3O4 as starting materials, a new low cost diatomite composite magnetic chitosan material was prepared by a simple method and studied for removal of Cr (VI) from waste water. Studied the effects of various parameters and studied adsorption kinetics, thermodynamic and isothermal model. The experimental results show that the adsorption capacity using diatomite composite magnetic chitosan material could reach 47.8mg/g at the best conditions, the situation is 15℃, pH=3, it is conducive to the adsorption at low temperature. Fitting the isothermal model, the Langmuir model provided well correlations of the experimental data, and kinetic data was well fitted by the pseudo-second-order model, the thermodynamics parameters of adsorption system indicated exothermic process. And the adsorbent can be recovered by adding NaOH solution after saturation.