The effects of Fe and Na impurities containing γ-Al2O3 catalyst on catalytic reaction of dimethyl thioether synthesis were investigated. The results indicated that the decomposition reaction of methyl alcohol was exacerbated as the Fe content increased. The mercaptan yield increased while dimethyl thioether yield decreased. The rate of decomposition of methyl alcohol increased as the Na content reduced. Both the maximum yield of dimethyl thioether and the minimum yield of methyl hydrosulfide were obtained in the Na mass fraction range of 0.2 %- 0.4%. When the Na content further increased, the yield of methy hydrosulfide increased, the selectivity of dimethyl thioether decreased.