Abstract: The ideal reactions and non-ideal reactions for reducing gasoline olefin and sulfur, and increasing propylene were proposed by analyzing potential secondary reactions of catalytically cracked gasoline. The secondary reactions of FCC nathpha on REUSY, ZRP and MO-REY zeolite catalysts were investigated in a FCC pilot plant with riser reactor to determine the product distribution of secondary reactions and properties of the upgraded gasoline. Effects of operating intensity on conversion and selectivity of gasoline secondary reactions were also investigated by experiments.The results indicated that lighter dry gas,LPG rich in propylene,heavier diesel and coke were produced by secondary reactions of FCC nathpha under the catalysis of Y or ZRP zeolite catalysts. In comparison with the FCC nathpha feeds, olefinicity and sulfur content of the upgraded gasoline derived from secondary reactions decreased greatly, and aromatics content and octane number increased evidently.Conversion and selectivity of gasoline secondary reactions depended on the olefin content of feed gasoline, the zeolite type of catalysts and the operating intensity of reaction process.