Aim By examining the level of CD45 protein expression in coronary atherosclerotic lesions, and to analyze the relationship between CD45 and lesions structure changes and explore the role of CD45 in the development of coronary atherosclerotic lesions in humans. Methods Specimens of coronary arteries were obtained from Forensic Judicial Expertise Center, Guizhou Medcial University with coronary atherosclerosis. The coronary arteries were classified into three groups according to the lesions:control, atherosclerosis, atherosclerosis and secondary lesion. Routine HE staining of paraffin sections was performed to observe the histological structure of coronary artery in the three groups. The expression level of CD45 protein was detected by immunohistochemical staining, Western blot and Real-time PCR. The relationship between the expression of CD45 and the structural changes of atherosclerotic lesions were analyzed. Results (1)Compared with the control group, the thickness of the fibrous cap in the coronary arterial plaque with atherosclerosis and secondary lesions became thinner, and the thickness of the lesion, the thickness of the necrosis lesion, and the lumen area of the vessel increased (P<0.05). (2)There was a statistically significant difference in the expression of CD45 protein between vascular tissues. (3)There was a statistically significant difference in the expression of CD45 between the control group, the atherosclerosis group and the secondary lesions, and it was mainly expressed in the all leukocytes of the plaques shoulder and bottom. (4)There was a statistically significant difference in the expression of CD45 mRNA between three groups. (5) CD45 expression was related to lesion structure changes. Conclusion The level of CD45 expression reflects the extent of inflammation in human coronary atherosclerotic plaque, and the extent of inflammation within the lesion can affect the structure of the lesion.