A combined desulfurization/denitration (DeSO(x)/DeNO(x)) process has recently been proposed by using the powder-particle fluidized bed (PPFB). In the process, SOx is removed by a fine DeSO(x) sorbent continuously supplied and NOx is reduced to N-2 by ammonia under the catalysis of a coarse DeNO(x) catalyst, the fluidization medium particles. By using the simplest model gas, SO2-NO-Air, in a laboratory scale reactor, SO2 and NO removals in the process are evaluated in this paper by testing the possible side reactions related to SO2 and NO. Then, investigations are extended to the removal efficiency for the simulated flue gas SO2-NO-N-2-H2O-Air and to the effects of operating conditions, both gas velocity and the static height of catalyst bed, upon the SO2 and NO abatements. The DeSO(x) sorbents used were CuO . V2O5. K2SO4/Al2O3 and NaHCO3, and the DeNO(x) catalysts were V2O5. WO3/TiO2 and WO3/TiO2. It was found that this process suffers little from SO3 exhaust at the reactor exit. SO2 may be chemically adsorbed onto DeNO(x) catalyst, but it can be suppressed by using a highly efficient sorbent such as CuO . V2O5. K2SO4/Al2O3. Under NH3/NO = 1, both NO and NO2 can be similarly reduced into N-2 and the possible side reactions between sorbent and NO, can also be completely abated by the NOx reduction. SO2 and NO removals in the process are more or less affected by water vapor and oxygen fractions, but the removals greater than 90% for SO2 and no less than 80% for NO can still be maintained for actual flue gas, even in a shallow bed with a static catalyst load height of 0.1 m.