Abstract: Objective: This study aimed to investigate the sleep-promoting effect and possible mechanism of volatile components from agarwood leaves. Methods: The aqueous extract of agarwood leaves was obtained by steam distillation; the volatile components were detected by gas chromatography-mass spectrometry(GC-MS) in the aqueous extract of agarwood leaves; insomnia model induced by p-Chlorophenylalanine (PCPA) was used to evaluate the sleep-promoting effect in mice of the aqueous extract of agarwood leaves; the levels of neurotransmitters glutamic acid (Glu), gamma-aminobutyric acid (GABA), and 5-hydroxytryptamine (5-HT) were detected by ELISA to explore the possible mechanism of sleep-promoting effect of agarwood leaf in serum. Results: Sixty-five volatile compounds were identified from the agarwood leaves, among which the main components (accounting for >1%) were twenty-one compounds (77.72%), including cinnamyl acetone, cis-1-methyldicyclopentane-2,10-dione, hexadecanoic acid, 6,10,14-trimethyl-2-pentadecanone, cis-3-hexenol benzoate, trans-geraniol, n-octanol, β-ionone, etc. The pharmacological study showed that the aqueous extract of agarwood leaves could significantly shorten the sleep latency of insomnia model mice (P<0.01), prolong the sleep time (P<0.01 or P<0.001), and had a good sleep-promoting effect; the aqueous extract of agarwood leaves significantly reduced the total distance and average speed in insomnia model mice (P<0.01) and prolonged the rest time (P<0.01), showing good inhibitory effect on the spontaneous activity; the aqueous extract of agarwood leaves could also significantly reduce the Glu level and increase the GABA and 5-HT levels (P<0.05 or P<0.01). Conclusion: The study shows that the aqueous extract of agarwood leaves have goood promote sleep effect, and its mechanism is related to regulate the secretion of neurotransmitters and control the balance of excitatory-inhibitory neurotransmitters (Glu-GABA).