Preparation method for catalytic cracking catalyst for cracking coker gas oil and increasing production of gasoline

The invention provides a preparation method for a catalytic cracking catalyst for cracking coker gas oil and increasing production of diesel. The preparation method comprises the following steps thata rare earth, phosphorus and magnesium modified Y-type molecular sieve is prepared, specifically, a NaY molecular sieve is subjected to ammonium salt and rare earth salt exchange and then is sequentially modified by phosphorus and magnesium, wherein the step is characterized in that phosphorus modification is carried out before magnesium modification; (2) the catalyst is formed, specifically, water, the molecular sieve, clay, pseudo-boehmite and a binder are mixed, pulped, spray-dried and roasted; and (3) modification is carried out, specifically, the water, magnesium salt and catalyst particles are uniformly mixed, the pH value is adjusted, and filtering and drying are carried out. The catalyst shows good heavy oil conversion capability and diesel selectivity in the process of cracking the coker gas oil.