Objective Exploring the effects and characteristics of Eucommia ulmoides bark and leaveson inflammation and blood-brain barrier damage in rats with depression. Methods? the chronic unforeseen mild stress (CUMS) was used to establish the rat model of depression, the SD The rats were randomly divided into normal group, depressed group, E.ulmoides bark group and E.ulmoides leaf group. Behavioral tests were carried out by using open field and Morris water maze experiments; HE staining and Nissl staining were used to observe the pathological morphology of the hippocampus (HP) of the rats; ELISA was used to detect the contents of IL-1β, IL-6, and TNF-α in the serum and hippocampus of the rats; immunofluorescence The expression levels of ZO-1 and occludin were detected by immunofluorescence. Results Compared with the control group, the target quadrant residence time, crossing platforms,the number of climbing frames and standing frequency of rats in the depressed group were significantly lower (P<0.05 or P<0.01); There are obvious cellular structural blurriness, inflammatory cell infiltration and damage, decreased or even disappeared Nissl bodies, and degeneration and necrosis of nerve cells in hippocampal tissue; the contents of IL-1β, IL-6, and TNF-α were significantly elevated(P<0.01); the positive expression of ZO-1 and occludin was reduced(P<0.05). Compared with the depressed group, the residence time in the target quadrant, the number of crossing platforms, and the number of climbing frames of rats in the E.ulmoides bark group were significantly higher (P<0.05 or P<0.01), the number of crossing platforms, the number of climbing frames and standing frequency ofrats in the E.ulmoides leaf group were significantly higher (P<0.05 or P<0.01);the pathological morphology was restored; and the contents of IL-1β, IL-6, andTNF-α in serum and hippocampus of the rats in the E.ulmoides bark and E.ulmoides leaf group were significantly lower(P<0.01 or P<0.05); positive expression of ZO-1 and occludin was elevated(P<0.05). Conclusion Both E.ulmoides bark and E.ulmoides leaves can significantly improve the behavior of depressed rats, regulate blood-brain barrier permeability, reduce inflammatory response damage, and thus protect neurological function.