Hydrocracking catalyst and its preparation method and use

The invention discloses a hydrocracking catalyst and its preparation method and use. The hydrocracking catalyst contains a MoY-type zeolite molecular sieve-containing carrier, wherein the n value of the MoY-type zeolite molecular sieve is greater 0 and less than 1, n=I/alpha I , by Ft-IR method-based characterization, I represents 3625cm absorption peak intensity in the Ft-IR spectrum of the MoY-type zeolite molecular sieve, I represents 3625cm absorption peak intensity in the Ft-IR spectrum of a mother Y-type zeolite molecular sieve, and alpha represents a ratio of 3740cm absorption peak intensity in the Ft-IR spectrum of the MoY-type zeolite molecular sieve to 3740cm absorption peak intensity in the Ft-IR spectrum of the mother Y-type zeolite molecular sieve. The preparation method comprises the following steps of 1, mixing a Mo-containing compound and a Y-type molecular sieve, and 2, calcining the mixture obtained by the step 1 in a vapor-containing atmosphere. Compared with the existing catalyst, in a diesel oil hydrogenation modification reaction process, the hydrocracking catalyst can obviously improve diesel oil aromatic hydrocarbon conversion and open loop product selectivity (for reducing open loop product secondary-cracking).