Abstract: To study the effects of squalene on behavior and related proteins of glutamate toxicity pathways in the mice with chronic unpredictable mild stress (CUMS), thirteen different kinds of CUMS were applied to the male BALB/C mice for 35 days to establish the mouse model of CUMS depression. The stress conditions include food deprivation, noise, stroboscopic lighting, hot stress (45℃), brake, exposure to lower temperature (4℃), shake, soiled cage, clamp tail, water deprivation, swimming, electric shock, presence of a foreign object in the home cage. The mice were treated with squalene at 3 doses (80, 40 and 20 mg·kg^-1·d^-1) through oral administration from the 3rd week continuously. Three weeks later, the impacts were evaluated in the mice with behavioral tests, and malondialdehyde (MDA) and hippocampal glutamate (GLU) contents, the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in hippocampus were measured by spectropho-tometry or reversed phase HPLC (RP-HPLC). Western blot was used to examine the expression level of N-methyl-D-aspartate receptor subunits epsilon-2 (NMDAε2), calmodulin kinaseⅡ (CaMKⅡ) and neuronal nitric oxide synthase (NOS1) in hippocampus. Compared with model group, the squalene-treated mice exhibited an increase in body weight, sucrose preference rate and the times of crossing-movement and rearing-movement, shortened the immobility time in the tails suspension test and forced swimming test in the depression mice (P<0.05). Meanwhile, the treated mice had a significant decrease in the contents of GLU and MDA (P<0.05) in hippocampus, increased the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and downregulated the expression of NMDAε2, CaMKⅡ and NOS1 in the hippocampus. In conclusion, squalene shows anti-depressant effect on depressant model in mice, meanwhile the downregulated ROS, related proteins of GLU-NMDAε2-CaMKⅡ-NOS1 signal pathways may be related to the antidepressant effect of squalene.