Abstract: Odor pollution is one of the environmental issues that produces the most intense complaints from urban residents in China. Investigation into the odor pollution and gaseous pollutants in the urban ambient air of Tianjin City was carried out. Using the grid method, 40 total monitoring sites covering various functional zones were uniformly allocated in the central urban area and a typical industrial area. In total, 1300 air samples were collected using intensive field sampling methods in each season. The chemical composition and olfactory concentrations in the air samples were respectively analyzed by GC-MS and triangle odor bag method. Ammonia was separately determined by spectrophotometry. The results showed that:1) Odor concentration values ranged from 0 to 90, and were equally matched between the urban and industrial areas. In summer, the highest percentage (42%) of odor concentrations were less than 10. The odor pollution was more serious in spring and autumn as compared with the other two seasons. In spring and autumn, the percentage of values with odor concentration over 20 was more than 85% and 70%, respectively. 2) Ammonia was the odorant with the highest detection rate. The average values of ρ(NH₃) in summer, autumn and spring were 0.070,0.058 and 0.060 mg/m³, respectively. The average value of ρ(NH₃) in the residential and the mixed areas were the highest among all types of functional zones. 3) The distribution of H₂S varied with seasons, with the highest detection rate in autumn. ρ(H₂S) was in the range of 0.0064-0.2200 mg/m³, with the highest value in the industrial area. The average concentrations in the urban and industrial areas were 0.0140 and 0.0230 mg/m³ respectively. The typical gaseous pollutants were selected by comprehensive and quantitative evaluation of multiple parameters such as environmental concentration, olfactory threshold and detectable rate. Ten volatile substances were identified as ammonia, carbon bisulfide, benzene, toluene, 1,3-dimethylbenzene, ethylbenzene, 1,2,4-trimethylbenzene, alcohol, acetone and isoprene. A multiple linear regression equation between odor sensory concentrations and the selected ten substances was set up, and showed good statistical significance and correlation (P<0.05, R=0.78). This result indicates that these gaseous compounds were the most important substances influencing odor pollution in the urban ambient air. The survey results may provide reference for the establishment of an odor environmental standard.