Compared with steaming cracking, catalytic cracking is more appealing with much lower reaction temperature and adjustable distribution of the product (by changing the catalyst composition). In order to obtain efficient catalysts with high selectivity to light olefins for petroleum catalytic cracking, composite ZSM-5-USY zeolites were modified with single metal (e. g., cerium, yttrium, zirconium, manganese, and copper) or bimetals (e. g., zirconium-cerium, manganese-cerium, yttrium-cerium, and copper-cerium) by incipient impregnation. The physicochemical properties, including crystal structure, acidity, surface area, of the catalysts were characterized by XRD, NH3-TPD and BET. Catalytic activity of the prepared catalysts in cracking were evaluated by using n-hexane as a model compound for petroleum on a fix-bed reactor. The composition of the product was detected online by gas chromatography. The results showed that the composite molecular sieves modified by various metals exhibited quite different catalytic behaviors in n-hexane cracking, and the performance had close relationship with acidity content of the catalyts. Catalysts with higher weak acidity amount exhibited higher conversion of n-hexane and selectivity of C2~C4 olefins. The Ce-Zr co-modified molecular sieve showed excellent catalytic activity and high selectivity of C2~C4 olefins (57%) at 550℃. Steam treatment had significant influence on the acidity of Ce-Zr/ZSM-5-USY and distribution of the cracking products. After steam treatment, stability of the catalyst was significantly improved, and selectivity of C2~C4 olefins increased from 20.02% (when there was no steam treatment) to 57.55% (when the catalyst was steam treated for 4 h), but the n-hexane conversion rate decreased. Kinetics study of cracking of n-hexane over 0.25% Zr-0.5% Ce/ZSM-5-USY showed that this reaction was a first order reaction, and the activation energy was 88.93 kJ/mol.