To study the pollution characteristics of volatile organic compounds (VOCs) in Tianjin downtown ambient air, 26 sampling points were distributed in Tianjin and systematic sampling was carried out in Spring, Summer, Autumn and Winter, respectively. More than 80 kinds of VOCs were detected which mainly included alkanes, BETX and halohydrocarbon with detection rates of over 80%. The total concentration of VOCs changed with the seasons, in the order of Spring (110.43 x 10(-9)) > Autumn (93.73 x 10(-9)) > Winter (73.37 x 10(-9)) > Summer (60.43 x 10(-9)). The result of concentration statistics indicates that the total concentration of VOCs in urban areas was in the range of 30 x 10(-9)-90 x 10(-9) and the number of samples in every season in this concentration range accounted for over 50%. There were also differences in the composition of VOCs with the change of seasons in Tianjin. Oxygenated organic compounds and hydrocarbons were the main substances of VOCs and the concentration percentage of them was over 50% in every season. Two main pollutants, BETX and halohydrocarbon, were analyzed for seasonal variation in this paper.