Abstract: During May 22 to December 31 of 2005,continuous measurements of some trace gases at Xinglong Station,atmospheric background observation network of Chinese Academy of Sciences were carried out.Some variation characteristics and variation regularity of O₃,NOx(NO,NO₂),CO₂,SO₂,and their present concentrations were obtained.In general,O₃ displayed a higher concentration in June and September,and the lowest concentration in December.NOx indicated the lowest concentration in August,and slowly increased during August to November,the ratio of NO to NOx is very low.SO₂ showed the lowest concentration in July,and then gradually increased.CO₂ exhibited the lowest concentration in August.Based on the present observation,good air quality at Xinglong Station is in July and August. and to study their interactions and the relations between them and solar radiation.