To detect the serum levels of B cell activating factor (BAFF) in patients with systemic lupus erythematosus (SLE) and to investigate the relationship among TCM pattern, BAFF and disease activity index in patients with SLE. Methods: The serum levels of BAFF were measured by ELISA in 91 SLE patients and 20 health control group. Patients with SLE also tested the erythrocyte sedimentation rate (ESR), complement 3 (C3), complement 4 (C4), C reactive protein (CRP). Results: 1) The levels of BAFF in SLE patients were significantly higher than those in the healthy control group (P<001), and the level of SLE disease activity group was significantly higher than that of the healthy control group and no activity group (P<001). 2) The levels of BAFF SLE patients showed a positive correlation with SLE disease activity index (SLEDAI)(r=0.73, P<001) and ESR (r=0.39, P<001), and showed a negative correlation with C3 (r=-0.34, P<001). 3) The levels of BAFF in the heat-toxin flourishing type of SLE patients compared with other TCM patterns were significantly increased (P<001), and the asthenic healthy qi with pathogen lingering pattern were significantly lower than other TCM patterns (P<001). Conclusion: In SLE patients, the levels of BAFF were significantly increased and correlated with SLEDA. The correlation with TCM patterns indicates that anti BAFF monoclonal antibody in different TCM pattern of SLE patients may have different curative effects.