Abstract: In order to improve the economic benefits of the FCCU in Yanshan Petrochemical Company, several technical reform measures for No.2 FCC unit processing heavy oil have been adopted. The operation changes after the reforming are discussed in detail. The technical measures include revamping the waste heat boiler（WHB） for energy saving and anti-corrosion, applying an airlift loop hybrid stripper, installing the fourth cyclone separating device and a new type of critical flow velocity injector, and a mid-reboiler in desorption tower. These measures enable the unit to have a long-term stable running. The economic benefits can be increased by more than 37 million yuan per year.