An annular denuder system(ADS), which consisted of denuder tubes striping the reactive gases from air and leaving the particles on the filters was designed. After sampling, the absorbed gases and particles were separately leached with water and determined by ion chromatography. The detection limit of samples was about 1.0 x 10(-4) mg/m3 for SO2, HNO2, SO4(2-) and NO3-. The loss of particles on the denuder faces was less than 5% and the collection effectiveness of particles was 100%. Absorbtion effectiveness for gases was more than 95%. The average RSD was less than 6.5%.