Abstract: In order to identify the sensory characteristics and emission differences among different odour emissions, three kinds of sources (paint factory, cigarette factory and magnolia bakery) were selected and analysed. Pertinent field surveys combined with laboratory analysis were conducted, with the purpose of obtaining the behaviour curve of hedonic tone for specific odour emissions and comparing the annoyance potential of the sources under investigation. A 9-point scale was used to determine the hedonic tone. For each kind of source sample, the concentrations to be presented to the panel members comprised a range of 5 or 6 dilution steps, which differed by a factor of approximately 3. Using a suitable curve-fitting procedure, a line could be fitted through the points obtained in the experiment. The specific odorants of the three sources were screened out. Typical pollutants for the paint factory:ethylacetate, p-diethylbenzene, ethylbenzene, m-xylene, butylacetate; typical pollutants for the cigarette factory:ethanol, naphthalene, 2-butanone, limonene, propane; typical pollutants for the magnolia bakery:ethanol, limonene, α-pinene, toluene, acetone. The fitting results showed a quadratic polynomial relationship between hedonic tone and odour concentration index for different odours. The hedonic values of both the cigarette and paint factories were negative and that the magnolia bakery was positive. The offensiveness of the odours from the cigarette factory and paint factory was enhanced with increasing concentration index. At the hedonic value of -2, which corresponds to moderately unpleasant, the odour concentrations were 26 and 30 for the paint and cigarettes factories. The annoyance potential was calculated by multiplying the odour index and the H value of the original sample. The annoyance potential of the above odour sources was as follows:paint factory -14.48, cigarette factory -14.17, magnolia bakery 11.77. The findings of this study provide a scientific basis for the classification of various odours and the development of odour impact criteria.