Objective: The aim was to study the chemical constituents of essential oil from the Guangxi mangrove Thespesia populnea (L.) Soland. ex Corr. leaf. Method: The essential oil was extracted by steam distillation.The constituents were separated and identified by GC-MS

and then the relative contents was calculated with area normalization. Result: Fourtyfour kinds of compounds were separated

37 kinds of compounds which accounted for 89.75% were identified. The principal chemical constituents are 1

2

3

5

6

8a-hexahydro-4

7-dimethyl-1-(1-methylethyl)-

(1S-cis)-Naphthalene (16.14%)

α-Farnesene (13.16%)

1-methyl-4-(5-methyl-1-methylene-4-hexenyl)-

(S)-Cyclohexene (8.12%) and n-Hexadecanoic acid (8.52%). Conclusion: The study provided scientific basis for giving full play to medicinal value of this mangrove.