Background: With the variation of modern medical mode from “disease medicine” to “health medicine,” the traditional Chinese medicine (TCM) aromatherapy befits an important part of the exclusive health service resource intended for the prevention of diseases, rehabilitation and health care in China. Liver depression and insomnia are among the human health conditions that are apparently treated by TCMs since the ancient Chinese period. Objectives: To study the mechanism of volatile oil in treating liver depression and insomnia. Materials and Methods: Through data mining, we found dried and immature tangerine peel as a prescription for treating liver depression and insomnia. Gas chromatography-mass spectrometry was achieved to control the chemical composition of the essential oil. The effects of dried and immature tangerine peel essential oil on sleep latency and sleep duration were also explored using a pentobarbital-induced sleep test in mice. Network pharmacology tactics was executed to determine the potential active ingredients and molecular mechanism of the dried and immature tangerine peel essential oil in treating liver depression and insomnia. Results: Dried and immature tangerine peel essential oil has both calming and tranquilizing effects. Based on the network pharmacology, it was foretold that essential oil were mostly employed to treat liver depression and insomnia with predicted functions convoluted in regulating several neurotransmitters, such as the gamma-aminobutyric acid in the neuroactive receptor-ligand signaling pathway. Conclusion: In this study, the effect of volatile oil from dried tangerine peel and immature tangerine peel on mice sleep was established, and the mechanism of action for treating liver depression and insomnia was preliminarily deliberated.