Lupus nephritis (LN) occurs with inflammatory lesion in patients suffering from systemic lupus erythematosus (SLE). Tumor necrosis factor (TNF) receptor associated factor 3 (TRAF3) is an important mediator in inflammation. To explore the roles of TRAF3 in LN, the LN mouse model was firstly established with intraperitoneal (i.p.) injection of pristine. Our results found that the amount of urinary protein was increased evidently at day 28, and renal damage occurred in the LN mouse model, but the TRAF3 knockdown reduced the urinary protein and alleviated the inflammatory lesion. The proinflammatory cytokines TNF-α, IL-1β, IL-17a, IFN-γ and IgM, IgG antibody were enriched, but there was little amount of IL-10 in the LN mouse model. Moreover, the amount of CD40+ B cells, CD4+ T cells sub-type, Th17 cells were abundant, and the proteins TRAF3, TRAF2, NF-κBp52, IKKα, ICAM1 in the kidney were highly expressed in the LN mouse model. However, TRAF3 knockdown enhanced the production of IL-10 and reduced the amount of pro-inflammatory cytokines, immunoglobulin, and the protein expressions of TRAF3, TRAF2, NF-κBp52, IKKα, ICAM1. In conclusion, TRAF3 plays a role in LN by regulating Th17 cell and Treg cell balance as well as NF-κB signaling pathway in mice.