Theδ13 C values of volatile organic compounds ( VOCs) in various emission sources and ambient air were analyzed by using thermal desorption coupled with gas chromatography and isotope ratio mass. The lowest sample concentration and peak shape quality needed for high precision and accurate analysis were investigated. Fuel evaporation ( gasoline and diesel) , vehicle exhaust, solvent evaporation, dining fumes and ambient air of different functional zones of Xiamen city were collected using Tenax TA tube, and the significant differences in δ13 C values of VOCs between these sources were observed. The δ13 C value of gasoline exhaust ( 97 # ) was heavier (-25 . 84‰) than that of dining fumes (-30 . 26‰) and theδ13 C values of fuel evaporation were heavier than that of vehicle exhaust after combustion. The average δ13 C value of atmospheric VOCs in Xiamen was at the level of -27 . 03‰ to -25 . 40‰, which was close to the δ13 C value of the evaporation and exhaust of gasoline and diesel, indicating that the VOCs in the atmosphere of Xiamen was highly influenced by transportation related sources.