The invention relates to a method for preparing a catalytic gasoline alkylate desulphurization complex catalyst. The catalyst developed by the method provided by the invention can be used for effectively removing a organic sulphur compound in gasoline. The technical scheme adopted by the invention is as follows: firstly adding an organic solvent into a container filled with absolute aluminium trichloride in the proportion that 1.5-4.0ml of the organic solvent is added into per g of absolute aluminium trichloride, and uniformly stirring; then introducing hydrogen chloride into the mixture, or adding one or two or three of dichloromethane, trichloromethane, tetrachloromethane and normal heptane, and reacting for 60-90 minutes at the temperature of 60-80 DEG C; and finally stopping stirring,wherein the reactants are divided into two phases, the upper phase is the organic solvent which can be recycled after being separated, the lower reactant is distilled at the temperature of 80-310 DEGC, and the residual product is the complex catalyst prepared by the method. The method provided by the invention has the advantages that raw material source is wide, reaction is carried out at normalpressure and lower temperature and is easy to implement, and the preparation method is applied to petroleum refining and chemical production.