The anhydrous aluminum trichloride catalyst and its preparation process are characterized by being composed of methylbenzene, solid aluminum trichloride and hydrogen chloride gas. When used, the catalyst of the present invention has strong activity, low dosage, low temperature reaction, wide applicability, and can replace solid aluminum trichloride catalyst. The dispersibility in the reaction is good, the reaction is complete, the product yield is increased by 5-10%, and the catalyst is stable in the reaction and easy to control. In addition, it has the advantages of simple manufacture, convenient use, pump delivery, and improved operating environment.