This paper studies NO₂,SO₂,and O₃ at Linan in summer and winter of 2003 and 2004.Results show that the mean volume fractions of NO₂ and SO₂ are 19.48×10^-9 and 35.74×10^-9 in winter,respectively,which are higher than those in summer(4.81×10^-9 and 8.12×10^-9, respectively).The mean volume fractions of O₃ is 33.55×10^-9 in summer,which is higher than that in winter (25.44×10^-9).The volume fractions of NO₂ and SO₂ during the daytime are lower than those during the nighttime.The diurnal variation of NO₂volume fraction shows the single valley and single peak distribution with its peak during the nighttime.The diurnal variation of O₃ volume fraction is similar to NO₂,but its peak appears during the daytime.The volume fractions of NO₂ and SO₂ show an obvious "Holiday Effect",and are obviously lower during weekends than those during weekdays,with the highest on Fridays.The volume fraction of O₃ does not have an obvious "Holiday Effect".The wet removal efficiency of precipitation to SO₂ is more obvious than to NO₂.By contrast with the different wind directions,the higher volume fractions of NO₂ and SO₂ are affected by NW and WNW winds in summer,while by NE,SW and SSW winds in winter.The influence of wind direction on the ozone is complex,which is relevant to local photochemical reactions.