Abstract: Objective To study the effect of diosmin (DOSM) on expression of PECAM-1 in kidney tissue of rats following ischemia/reperfusion (I/R) injury and its kidney protection mechanism. Methods One hundred and fifty SD rats were randomly divided into sham operation (SO) group, I/R group, and DOSM +I/R group. Expression level of PECAM-1 in kidney tissue was measured by immunohistochemistry and Western blot, respectively, at different time points of I/R. Results The expression level of PECAM-1 in kidney tissue increased gradually at 1, 6, 12, 24, and 48 h in I/R group and DOSM+I/R group, reached its peak at 48 h, and was significantly lower in DOSM +I/R group than in I/R group (P＜0.01, P＜0.05). No significant difference was found in the expression level of PECAM-1 measured by Western blot and immunohistochemistry. Conclusion DOSM can significantly downregulate the expression of PECAM-1 in rats following I/R injury and alleviate the infiltration of inflammatory cells, thus improving I/R injury and protecting renal function.