In this paper, the influence of particle size of ZSM-5 zeolites on the yield of propylene and physicochemical properties of catalysts in fluid catalytic cracking reaction was investigated. Two kinds of ZSM-5 zeolites with different sizes, small particle and routine, were utilized to prepare the catalysts. The particle size of small particle and routine ZSM-5 zeolites was 1.99 mu m and 5.48 mu m, respectively. The attrite index of catalyst including small particle ZSM-5 zeolites was far lower than that of routine zeolites. More propylene and more clean gasoline can be obtained when the small particle ZSM-5 was used as a component of catalyst. The suitable content of small particle ZSM-5 zeolites remained the cracking activity of heavy oil, and at the same time, was helpful for the enhancement of propylene yield. (C) 2010 Published by Elsevier B.V.