To study the air pollution in Tangshan City and its effects on Beijing and the surrounding areas during the Beijing Olympics, the on-line monitoring of atmospheric pollutant was performed at the summer and autumn time in 2007 and 2008 in Tangshan. The results show that the average PM2.5 concentrations are 105.1 microg x m(-3) +/- 46.5 microg x m(-3) in summer and 108.1 microg x m(-3) +/- 61.8 microg x m(-3) in autumn. The average max hourly O3 concentrations are 153.9 microg x m(-3) +/- 50.9 microg x m(-3) in summer and 114.6 microg x m(-3) +/- 56.5 microg x m(-3) in autumn. The average NO2 concentrations are 39.2 microg x m(-3) +/- 10.0 microg x m(-3) in summer and 42.7 microg x m(-3) +/- 11.6 microg x m(-3) in autumn, and the average SO2 concentrations are 44.8 microg x m(-3) +/- 31.1 microg x m(-3) in summer and 52.2 microg x m(-3) +/- 25.2 microg x m(-3) in autumn. The average oxidant (NO2 + O3) concentrations are 111.9 microg x m(-3) +/- 27.0 microg x m(-3) in summer and 87.2 microg x m(-3) +/- 27.8 microg x m(-3) in autumn. As one of the fine particles sources in areas of Beijing, Tianjin and Hebei, Tangshan is severely polluted by fine particles; Concentrations of SO2 and NO2 are higher than that of surrounding areas, but still attain the national standard for Grade II. Long-term NO2 concentration which mainly comes from automobile exhaust changes little. The O3 concentration is relatively low compared to nearby areas, however, it remains unknown how high local emission of O3 precursor (NOx) would affect the regional O3 production. During the Beijing Olympics, affected by industrial emission reduction, all air pollutant concentrations were reduced especially SO2 and PM2.5, so reducing industrial emission should be useful for improving air quality in Tangshan.