Objective: To analyze the chemical constituents of volatile oil from Ocimum basilicum collected in two different sources. Method: The volatile components were extracted by steam distillation method

and analyzed by GC-MS. Peak area normalization method was used for the relative content of volatile oil. TLC was used for the identification of two samples. Result: Twenty-nine components were identified in O. basilicum from Guangzhou

which accounted for 99.90% of the total relative content.The main components were p-allylanisole (83.082%)

linalool 4.734%)

tau-cadinol (2.715%)

eucalyptol (2.251%). Thirty-one components were identified in O. basilicum from Bozhou

which accounted for 98.65% of the total relative content. The main components were linalool (26.91%)

methyl cinnamate (21.85%)

tau-cadinol (17.41%)

ledol (14.154%). Two characteristic spots could not be identified in O. basilicum from Bozhou but from Guangzhou. Conclusion: The volatile oil from different sources had obviously different chemical constituents. GC-MS and TLC can be used for the identification and analysis of sources. It pointed out that O. basilicum should clear about its quality and sources before exploitation and application.