Abstract: Based on the comparison of several FCC flue gas desulfurization and denitrogenization technologies, Sichuan Petrochemical Limited Liability Co. CNPC introduced Belco Company`s EDV ? desulfurization and LoTOXTM wet washing denitration technology for its 2.5 Mt/a catalytic cracking unit. By the technologies, the concentration of SO2 is reduced from 2020 mg/m3 to 35 mg/m3, the nitrogen oxides are lowered from 300 mg/m3 to 26 mg/m3and the catalyst particles are reduced from 150 mg/m3 to 20 mg/m3. The reduced amount of SO2, NOX and particles in the discharged flue gas are reduced significantly by 4 625 t/a, 638 t/a and 303 t/a, respectively. The pH, COD and total suspended solids of the discharged waste water are much lower than the design emission standards.