Objective · To explore the characteristics of B cell subsets in rheumatoid arthritis (RA) patients and the regulation of epigallocatechingallate (EGCG) on B cell subsets in RA patients. Methods · Twenty-nine age- and sex-matched RA patients and 29 healthy controls were selected, and the difference of B cell subsets in peripheral blood between the two groups was analyzedpaired t-test. According to the value of disease activity score in 28 joints (DAS28), RA patients were divided into active group (2.6≤DAS28<5.1) and highly active group (DAS28≥5.1). The differences of B cell subsets in peripheral blood between the two groups were analyzedt test. Peripheral blood mononuclear cells were cultured in vitro under co-stimulation of 0, 10, 100 μmol/L EGCG and 2.5 μg/L staphylococcal protein A. The level of B-cell-activating factor receptor (BAFF-R) mRNA was detectedreal-time PCR after 24 h, and B cell subsets were detectedflow cytometry after 48 h. Results · The numbers and the proportions of total B cells, undifferentiated B cells,memory B cells and plasmablasts in lymphocytes of RApatients were significantly higher than those of healthy controls (P<0.05), which of CD19+ IL-10+ regulatory B cells (Breg) of RA patients were not significantly different those of healthy controls (P>0.05). There was no significant difference in the numbers and the proportions of total B cells and B cell subsets (except CD19+ IL-10+ Breg) between 10 RA patients of active group and 19 RA patients of highly active group (P>0.05). There was no significant difference in the number and the proportion of CD19+ IL-10+ Breg in lymphocytes between 6 RA patients of active group and 12 RA patients of highly active group (P>0.05). The proportion of total B cells was weakly positively correlated with IgG type rheumatoid factor (r0.308). EGCG could significantly increase the proportion of CD19+ IL-10+ Breg (P<0.05) and 100 μmol/L EGCG could significantly suppress the of BAFF-R mRNA in B cells (P0.000). However, it had no significant effect on the proportions of undifferentiated B cells, memory B cells and plasmablasts in lymphocytes (P>0.05). Conclusion · B cells may play an auxiliary role in the development of RA. The number of CD19+ IL-10+ Breg in RA patients increases as a feedback. EGCG can promote Breg proliferation and suppress BAFF-R mRNA .