The invention relates to a hydrocracking catalyst and a preparation method thereof. The hydrocracking catalyst consists of hydrogenation active metal and a carrier structured by a modified composite molecular sieve and amorphous aluminium silicate; the hydrogenation active metal is molybdenum and/or tungsten, and/or cobalt, and/or nickel; the molybdenum and/or the tungsten accounts for 15.0-30.0% of the weight of the catalyst as weighed by oxide; the cobalt and/or the nickel accounts for 4.0-8.0% of the weight of the catalyst as weighed by oxide; the balance is the carrier structured by the modified composite molecular sieve and amorphous aluminium silicate; and the modified composite molecular sieve accounts for 10-20% and the amorphous aluminium silicate accounts for 80-90% by metering as the weight of the catalyst. The catalyst has the advantages that the raw materials are cheap and easy to buy; the preparation process is simple and easy to operate and has no generation of poisonous and harmful substances; the adaptability directing at the feature change of the raw materials; and the catalyst is suitable for experiment research on the existing hydrocracking process technology, can effectively solve the laboratory research difficulty and provides a reliable guarantee for the research and implementation of the hydrocracking process technology.