Abstract: Depression is one of the diseases with the highest disability rate in the world. A large number of studies have shown that the intake of unsaturated fatty acids can deal with depression while chronic overconsumption of saturated fatty acids is a risk factor for depression. It was suggested that the mechanism of saturated fatty acids inducing depression is related to the following four aspects:regulating the function which links to depression in whole brain and specific brain regions, including the hippocampus, the hypothalamic-pituitary-adrenal axis, the striatum, and the prefrontal cortex; stimulating the secretion of inflammatory factors; affecting the balance and function of metabolic regulatory hormones, including leptin, adiponectin, glucocorticoid, and insulin; inducing the disturbance of intestinal flora. This article reviews the relationship between dietary fatty acids and depression, and the possible mechanisms by which saturated fatty acids induce depression from the four aspects mentioned above.