To investigate the efficacy and mechanism of action of Compound Chaijin Jieyu Tablets (复方柴金解郁片, 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, positive drug (venlafaxine hydrochloride + diazepam), CCJJYT high-dose (CCJJYT˗2×), medium-dose (CCJJYT˗1×), and low-dose (CCJJYT˗0.5×) 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 pathological tissue and synaptic morphology, respectively. Enzyme-linked immunosorbent assay (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 immunohistochemistry 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 positive 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.