Objective:To investigate the inhibition of N-acetylcysteine(NAC) on the inflammation of diabetic nephropathy rats. Methods:A rat model of DN was established. The rats were divided into control group,DN group and NAC group randomly. Urinary albumin excretion rate(UAER),hs-CRP,IL-6 and TNF-α in serum were determined. The expression of NF-κB in renal tissue was detected by immunohistochemistry 8 weeks after treatment. Pathomorphologic changes of nephridial tissues were observed. Results:①Compared to control group,UAER,hs-CRP,IL-6 and TNF-α in serum were significantly higher(P < 0.01 or P < 0.05),activity of NF-κB in nephridial tissue increased(P < 0.01 or P < 0.05) and significant changes of pathomorphology in nephridial tissues were observed in DN group and NAC group. ②Compared to DN group,UAER,hs-CRP,IL-6 and TNF-α in serum were significantly lower(P < 0.05),activity of NF-κB in nephridial tissue was lower(P < 0.05) and improvement of pathomorphology in nephridial tissues were observed in NAC group. Conclusion:The protective effect of NAC on the kidney of the DN rats may be partly related with the inhibition on inflammation.