Abstract: In order to solve the problem that the gasoline pool olefins of PetroChina Lanzhou Petrochemical Company can't meet the national Ⅵ (B) standard of ethanol gasoline blending component oil, the MIP process technology reformation was carried out on the 3×10⁶ t/a heavy oil catalytic cracking unit. The MIP process technology was a new type of reaction system in the form of a series riser reactor developed by the Sinopec Research Institute of Petroleum Processing. The second reaction zone was connected in series through the riser to enhance hydrogen transfer and isomerization reactions, thus achieving the purpose of reducing gasoline olefin content and increasing the gasoline octane number. The device has been running smoothly since it was first started in June 2019. By comparing and analyzing the main economic and technical indexes such as olefin content in gasoline, RON, steam consumption, economic performance, etc. before and after technological transformation, the olefin volume fraction in gasoline reached the design requirements, which was 7.2% lower than before the transformation, the RON increased by 1 unit, and the steam consumption of the reaction regeneration system reduced by 8.3 t/h. The device operation optimization and economic improvement also had good effects.