Preparation of solid acid catalyst from AlCl3 Lewis acid and montmorillonite by ion exchange method, the effect of modification conditions and exchanger types on catalytic results were also studied. All kinds of physical properties of montmorillonite before and after modification were measured by XRD, shows that the original soil, after treating with Lewis AlCl3, expand its layer space from 1.471 3 to 1.522 5 nm, the surface area of 120 to 239 m2/g, pore volume from 0.140 mL/g to 0.322 mL/g. The catalytic reaction on synthesis of ethylene glycol shows that the optimum condition is as follow: reaction temperature 65 ℃, reaction time 30 min, the amount of catalyst 4%, the ratio of methanol to epoxyethane 4∶1 under normal pressure. In this process, the yield of glycol ethers was 90.5%, conversion rate of ether was 96.0%, the selectivity for single-ether 94.2%, which testified solid acid catalyst is good for synthesis of ethylene glycol.