Method for preparing in-situ crystallization type catalytic cracking catalyst The method comprises: (1) using kaolin as a raw material to prepare in-situ crystallization products: adding deionized water, a binder, a poly dimethyl diallyl ammonium chloride auxiliary agent into kaolin, obtaining kaolin spray microballoons by spray drying prepared mixed seriflux, roasting, mixing roasted microballoons with a guiding agent, and then obtaining the in-situ crystallization products with 50-70% of NaY zeolite after hydrothermal crystallization, filtration, washing with water and drying, wherein the adding amount of poly dimethyl diallyl ammonium chloride auxiliary is 1-10% of the quantity of kaolin; (2) exchanging and roasting the in-situ crystallization products: fully mixing the in-situ crystallization products and 0.01-3N acid solution in a liquid-solid mass ratio of 4-15:1 under 20-100 DEG C, regulating a pH value in a range of 2.8-6.0, treating for 10-100min, then adding one or more of ammonium salts, rare earth or phosphor for exchanging, and roasting, to obtain the in-situ crystallization type catalytic cracking catalyst.