Objective: To study the chemical constituents and antibacterial activity of essential oil from the flowers of Wedelia trilobata. Method: The essential oil from the flowers of W. trilobata was extracted by steam distillation. The components of the essential oil were separated and identified by gas chromatograph-mass spectrometer (GC-MS). Its antibacterial activity against six species of strains (Escherichia coli

Bacillus cereus

Bacillus subtilis

Pediococcus

Sarcina lutea

Staphylococcus) was evaluated by microdilution method. Result: 61 chromatographic peaks were detected and 57 components were identified and accounted for 92.92% of all the peak area. The essential oil showed well inhibitory activities against B. subtilis and S. lutea

with minimum inhibitory concentration (MIC) values of 0.39 and 0.78 mg·L-1

respectively. Conclusion: The essential oil was extracted and the chemical constituents were identified for the first time

and found that is rich in diversity of sesquiterpenes. This study provides experimental evidence for the further research and exploitation of W. trilobata.