To investigate the efficacy and mechanism of action of Compound Chaijin Jieyu Tablets (, CCJJYT) in rats with insomnia complicated with depression. Seventy-two Sprague-Dawley rats were randomly assigned into eight groups: the control, chronic unpredictable mild stress (CUMS), sleep deprivation (SD), CUMS + SD, pos. drug (venlafaxine hydrochloride + diazepam), CCJJYT high-dose (CCJJYT2x), medium-dose (CCJJYT1x), and low-dose (CCJJYT0.5x) groups, with nine rats in each group. Depression-like behavior was evaluated by body weight, food intake, and behavioral tests such as the sucrose preference test (SPT), open field test (OFT), forced swimming test (FST), and pentobarbital-induced sleep test (PST). Hematoxylin-eosin (HE) staining and Golgi-Cox staining were used to observe changes in pathol. tissue and synaptic morphol., resp. ELISA (ELISA) was used to detect the contents of orexin-A and acetylcholine. The expression levels of orexin receptor 1 (OXR1), melatonin receptor 1 (MT1A), melatonin receptor 2 (MT1B), acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) were detected by immunohistochem. and Western blot. In the present study, rats in the model group showed significant behavioral changes as well as a reduction in hippocampal dendritic branch length and synaptic number, along with increasing the content of orexin A and acetylcholine (P< 0.05), and altered expression levels of OX1R, MT1A, MT1B, ChAT, and AChE in the hippocampus and prefrontal cortex after modeling (P < 0.05). CCJJYT can improve depressive insomnia behavior and synaptic plasticity of rats (P < 0.05), which is similar to that of the pos. drug group. It can also decrease the content of orexin A and acetylcholine, and reduce the expression levels of OXR1 and ChAT in hippocampus and prefrontal cortex (P < 0.05), and increase the expression levels of MT1A, MT1B, and AChE proteins (P < 0.05). CCJJYT has good antidepressant and insomnia effects, probably through the regu-lation of orexin-A, melatonin, and acetylcholine content in hippocampus and prefrontal cortex of rats, improving synaptic plasticity and thus exerting antidepressant and insomnia effects.