Objective：To explore the effects of S100A9 knockout on mice with lupus nephritis（LN）induced by pristane，and clarify specific roles of S100A9 in LN. Methods：Ten female wild-type（WT）C57BL/6（B6）mice and ten S100A9^-/- B6 mice（6-8 weeks old） were used. Five WT B6 mice and five S100A9^-/- B6 mice were intraperitoneally injected with 0.5 mL pristane，respectively，serving as experimental groups. Other five WT B6 mice and five S100A9^-/- B6 mice were intraperitoneally injected with 0.5 mL normal saline， respectively，serving as control groups. The mice were sacrificed at six months after injection. The expression of anti-double-stranded DNA（ds-DNA）antibody was measured by ELISA. The levels of serum creatinine，serum urea nitrogen and urine protein were detected. Renal tissues were collected for HE staining to evaluate renal pathology. Results：There were no significant differences between WT and S100A9^-/- B6 mice on mouse body-weight，spleen weight，kidney-structure，and serum creatitine levels etc. Compared with control B6 mice，pristane treated B6 mice showed increased weight and length of spleen as well as increased levels of serum creatinine，urea nitrogen，proteinuria，anti-ds -DNA antibody and IgG，and the lupus -like changes in the kidney with increased glomerular volume， edema or renal tuble epithelium，and stenosis of lumen. Similar results were observed in pristane-treated S100A9^-/- B6 mice，compared with control S100A9^-/- B6 mice. However，compared with pristane -treated WT B6 mice，the above symptoms of LN and indexes of serum and urine were mild in pristane-treated S100A9^-/-B6 mice. Conclusion：Pristane induces systemic lupus erythematosus in B6 mice and S100A9^-/- B6 mice. However，the degree of lesions in mice with S100A9 gene knockout is reduced，suggesting that this gene may have a promoting effect on the pathogenesis of lupus in mice.