Objective:To provide the foundation for reasonable utilization by analyzing the volatile constituents of Cynanchum stauntonii. Method: The volatile oil was extracted from C. stauntonii by steam distillation. The chemical constituents were analyzed by GC-MS. Result: Thirty-seven compounds were separated and twenty-nine of them were identified

which accounted for 87.28% of all the volatile oil. The major components were hexanal (25.728%)

2-pentyl-furan (15.509%)

1-nonen-3-ol (4.025%)

(Z)-2-nonenal (3.577%)

1-caryophyllene (3.527%)

(+)-camphor (3.198%)

(E)-2-octenal 2.501%

borneol (2.025%)

2-methyl-5-(1-methylethyl)-phenol (2.980%)

3-methyl-4-isopropylphenol (2.333%)

a-gurjunene (2.156%). Conclusion: The composition of volatile oils of C. stauntonii was determined by GC-MS to provide the fondation for reasonable utilization of C.stauntonii.