Folic acid is a vitamin with a variety of pharmacological effects. The present study aims to explore the beneficial effects of folic acid on chronic unpredictable mild stress (CUMS)-induced depression-like behaviors and its possible mechanisms. The behavioral tests including open-field test, tail suspension test, and forced swimming test were used to evaluate the antidepressant effects of folic acid. Then the changes of brain 5-hydroxytryptamine (5-HT) concentration, brain-derived neurotrophic factor (BDNF), glutamate receptor 1 (GluR1) expression levels, and synaptic organization were assessed to explore the antidepressant mechanisms of folic acid. Our results showed that CUMS caused significant depression-like behaviors, neuropathological changes, and decreased brain 5-HT concentration, BDNF, and GluR1 expression in the hippocampus and association cortex. In conclusion, the results showed that folic acid significantly improved depression-like behaviors in CUMS-induced rats, and its antidepressant effects might be related to the increase of brain 5-HT concentration, BDNF and GluR1 expression, and repair of synaptic organization in the brain.