Abstract: The USY fluid catalytic cracking catalyst was modified by Ce_2O_3, La_2O_3 and P_2O_5 for changing acidic properties of the matrix and zeolite to improve the performance of catalytic cracking and hydrogen transfer. The introduction of rare earth increased acid amount of the matrix and zeolite, and promoted catalytic cracking reaction and hydrongen transfer reaction, but high content of rare earth also promoted the producing of coke. The addition of phosphorous optimized the acidic properties of the matrix and zeolite, by decreasing the amount of stronger acid and increasing the amount of weaker acid to obtain the low coke yield while promoting hydrongen transfer reaction.