Objective:To analyze the distribution of peripheral blood B cell subsets in patients with systemic lupus erythe-matosus(SLE)and their clinical applications.Methods:52 SLE patients(SLE group),36 healthy controls(HC group)and 30 rheumatoid arthritis(RA group)patients were included.The percentage of B1,FOB,Breg and ABC cells in total B cells was measured by Flow cytometry.Diagnostic efficacy of individual and combined B cell subsets for SLE was evaluated via ROC curves.Clinical data on SLE activity score(SLEDAI),erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),com-plement C3 and C4,immunoglobulin,and various autoantibodies from SLE patients were collected,and the correlations between the subsets percentage and these indicators were analyzed.Results:Compared to HC group,the percentage of B1,Breg,and ABC were higher in SLE group(P<0.05)and the percentage of FOB was lower(P<0.05).The percentage of B1,and Breg in SLE group were obviosly higher than those in RA group(P<0.05)and FOB was lower(P<0.05).There was no statistically sig-nificant difference in the proportion of cells in each subgroup between the RA group and the HC group(P>0.05).ROC curve analysis showed that all B cell subgroups had a certain diagnostic efficacy for SLE,and the combination of multiple subgroups had a higher diagnostic efficacy for SLE.The area under the curve(AUC)of 11 combinations for diagnosing SLE was 0.756～0.892(P<0.05),with(ABC+B1+Breg+FOB)combined was highest.Results of Assay of correlations showed that the per-centage of ABC cells positively correlated with the level of ESR(P<0.05,r=0.403).The percentage of Breg cells negatively correlated with the level of C3(P<0.05,r=-0.421)and positively correlated with the level of anti-dsDNA(P<0.05,r=0.488),anti-M2(P<0.05,r=0.604),SLEDAI(P<0.05,r=0.353).ABC and FOB were negatively correlated in the SLE group(P<0.05,r=-0.571),while there was no correlation between the two in the HC and RA groups(P>0.05).Conclu-sion:There are differences in the distribution of B cell subsets between SLE patients and the normal population.The combina-tion of single or multiple indicators has good diagnostic efficacy for SLE,and the distribution of subsets is correlated with multi-ple clinical and laboratory indicators,suggesting that it may have value in disease diagnosis and disease assessment.