One embodiment of the invention provides a modified Y-type molecular sieve and a preparation method thereof, wherein the modified Y-type molecular sieve comprises 4-11 wt% of rare earth (calculated asrare earth oxide), not more than 0.5 wt% of sodium (calculated as sodium oxide), 0.5-5 wt% of zinc (calculated as zinc oxide), and 0.05-10 wt% of phosphorus (calculated as phosphorus pentoxide), theskeleton silicon-alumina ratio is 7-14 based on SiO2/Al2O3 molar ratio, the mass of the non-skeleton aluminum accounts for not more than 10% of the total aluminum mass, and the pore volume of secondary pores with a pore size of 2-100 nm accounts for 20-40% of the total pore volume. According to the invention, the modified Y-type molecular sieve has advantages of high crystallinity, high thermal stability, high hydrothermal stability and rich secondary pores, is used for catalytic cracking of hydrogenated LCO (light cycle oil), and has advantages of low coke selectivity and high conversion efficiency of reactants.