Abstract: Objective To study the distribution of high mobility group box 1 (HMGB1) in aorta of normal mice and aorta atherosclerotic plaque of high fat fed ApoE^-/-mice and its expression in atherosclerosis at different stages． Methods Twelve 8-weekold SPF C57BL/6 male mice and twelve C57BL/6 ApoE^-/-male mice were used as control group and experimental group, each group was divided into two subgroups, the early and medial stage group (10 weeks high fat diet) and late stage group (20 weeks high fat diet)． After feeding for 10 weeks and 20 weeks, the mice were sacrificed． Aortic sinus frozen sections for oil red O staining was used to assess plaque size, macrophage immunohistochemical staining for localization of macrophages and aortic sinus paraffin sections for immunohistochemical staining to detect the expression of HMGB1． Results HMGB1 in normal mice aorta mainly expressed in endothelial cells nucleus, while in aorta atherosclerotic plaques of ApoE^-/-mice it mainly expressed in nucleus and cytoplasm of endothelial cells and macrophages, and also a small amount in smooth muscle cell nuclei; HMGB1 expression in early and medial stage atherosclerosis was higher than advanced atherosclerosis (0．05±0．067 vs 0．02±0．053)． Atherosclerotic plaque area ratio in advanced stage was higher than early stage (0．40±0．03 vs 0．25±0．02)． Macrophages were located in the intima, as the main component of plaque． Conclusion HMGB1 in atherosclerotic plaques mainly expresses in endothelial cells and macrophages; The expression of HMGB1 in atherosclerosis is higher in early and medial stage than advanced stage．