Objective: To study the rapid antidepressant effects of cannabioiol(CBD) on depression-like mice and its possible mechanism. Methods: Chronic restraint was used to establish a mouse depression model. The test mice were divided into 5 groups: normal control group, model group, positive control group, CBD low-dose group (25 mg/kg) and CBD high-dose group(50 mg/kg). The mice in each group were given intragastric administration one hour before the behavioral experiment. After the behavioral experiment, the hippocampus and prefrontal cortex specimens were collected, and brain-derived neurotrophic factor(BDNF), postsynaptic density protein 95(PSD-95), synaptophysin(SYP) and target of rapamycin(mTOR) were tested by ELISA. Results: Compared with the model group, the central area activity distance percentage, the central area activity time percentage and total distance increased in the open field experiment in the CBD low-dose group. Compared with the model group, the percentage of immobility in the forced swimming experiment in the low-dose CBD group decreased. The ELISA test results showed that CBD could rapidly increase the concentration of BDNF and PSD-95 in the prefrontal cortex, as well as the concentration of SYP and mTOR in the hippocampus and prefrontal cortex. Conclusion CBD can rapidly improve the behavioral performance of depression-like mice, and rapidly up-regulate the level of BDNF and synaptic protein in the hippocampus or prefrontal cortex.