【Abstract】 Objective To investigate the changes of serum level of oxidative stress marker late oxidative protein product (advanced oxidation protein products, AOPP) in patients with lupus nephritis (lupus nephritis, LN) and its correlation with lupus nephritis disease activity. Methods From January 2015 to December 2017, 80 patients with lupus nephritis and 80 patients with systemic lupus erythematosus were selected as lupus nephritis group and simple lupus erythematosus group. Sex matched with the observation group of 80 healthy volunteers? set up as the control group. Serum creatinine, urea nitrogen and serum AOPP levels were measured in fasting peripheral venous blood and fresh morning urine from three groups. The serum creatinine and urea nitrogen in lupus nephritis group, simple lupus nephritis group and control group were compared, and the serum creatinine and urea nitrogen were compared between lupus nephritis group and control group. Glomerular filtration rate (GFR) , 24 hour urinary protein quantification and serum AOPP level. Systemic lupus erythematosus disease activity index (systemic lupus erythematosus disease activity index, SLED Al) was used to evaluate the disease activity of patients with lupus nephritis. The patients with lupus nephritis were divided into mild active group, moderate active group and severe active group. Serum creatinine,urea nitrogen, glomerular filtration rate, 24 hour urinary protein quantification, serum AOPP level, serum creatinine , urea nitrogen ,glomerular filtration rate and 24 hour urine protein were compared in patients with lupus nephritis with different disease activity. The correlation between serum AOPP and lupus nephritis disease activity was analyzed. Results Serum creatinine , ureanitrogen , 24-hour urinary protein quantification , and serum AOPP in the lupus nephritis group were all higher than those in the lupus group and the control group (p＜0.05) , and their glomerular filtration rate was lower than those in the lupus group and the control group (p＜0.05). Comparison of serum creatinine , urea nitrogen , glomerular filtration rate and 24-hour urinary protein quantification between the lupus group and the control group showed no statistical significance (p〉0.05) , while serum AOPP level in the lupus group was higher than that in the control group (p＜0.05). After correlation analysis , it was found thatbothserumcreatinine ureanitrogen 24-hoururinaryproteinquantiicationandserum AOPPwerepositivelycorelatedwith the occurrence of lupus nephritis , r=0.846 , 0.837 , 0.829 and 0.859 , and the glomerular filtration rate was negatively correlated with the occurrence of lupus nephritis , r=0.831 , p＜0.05. The comparison of serum creatinine , urea nitrogen , glomerular filtratio4rate 24-houruri4aryprotei4qua4tificatio4a4dserum AOPPi4themild moderatea4dsevereactivitygroupsshowed statistically significant differences(p＜0.05). (4) after correlation analysis , it was found that serum AOPP levels of creatinine , urea nitrogen , 24-hour urinary protein and serum were positively correlated with the disease activity of lupus nephritis ( r= 0.829 , 0.817 , 0.804 , 0.835) and the glomerular filtration rate was negatively correlated with the disease activity of lupus nephritis (r=0. 823 ,p＜0.05). Conclusion The level of serum AOPP in patients with lupus nephritis is abnormally high. The higher the disease activity , the higher the level of serum AOPP. Serum AOPP can be used as an auxiliary index for the early diagnosis of lupus nephritis and the judgement of the disease condition.