BACKGROUND Lupus nephritis (LN) is the most common complication of systemic lupus erythematosus (SLE), and the abnormal activation of the alternative complement pathway is associated with the pathogenesis of LN. As an inhibitor of complement factor B (CFB) in the alternative pathway, LNP023 has been used in the treatment of a variety of renal diseases with abnormal complement system involvement, such as paroxysmal nocturnal hemoglobinuria, IgA nephropathy, and membranous nephropathy. The aim of our study was to explore whether LNP023 improved LN in MRL/lpr mice by inhibiting the activation of the alternative complement pathway. METHODS The mice were divided into a normal control group (Normal group) (n = 6), MRL/lpr model group (n = 6), and LNP023 group (n = 6). The LNP023 group was administered LNP023 for 2 weeks by gavage; the MRL/lpr model group was administered saline for 2 weeks by gavage; and the Normal group was administered saline for 2 weeks by gavage. External signs, renal pathology, renal function, renal immune complex and complement deposition, serum anti-dsDNA, serum ANA concentration, and the expression of core complement factors in the alternative complement pathway were analyzed in the 3 groups of animals. The core targets of LNP023 in the treatment of LN were screened using network pharmacology. The pathogenicity of the core targets in LN was verified by analyzing the mRNA expression of the core targets in the peripheral blood mononuclear cells (PBMCs) of normal individuals, SLE patients, and LN patients. The mRNA and protein expression of core targets in the Normal group, MRL/lpr group, and LNP023 group were analyzed to verify whether LNP023 exerted it LN therapeutic effect through the regulation of core targets. RESULTS Compared with the MRL/lpr group, the LNP023 group had reduced lupus-like signs, improved renal function, decreased serum anti-dsDNA and ANA concentrations, and reduced renal IgM, IgG, IgG1, C1q, C3, and C4 deposition. Renal pathology showed that LNP023 attenuated pathological damage in the kidneys of MRL/lpr mice. Compared with the MRL/lpr model group, the treatment group had no crescent formation, less immune deposition, no nuclear fragmentation, and less inflammatory cell infiltration. The expression of complement proteins C3, C3b, CR1, CFB, and C5b-9 in kidney tissues and liver was decreased, and the expression of C5 was increased. Network pharmacology screening indicated that AKT, TNF-α, MDM2, UBC, STST3, ESR1, and TP53 were core targets of LNP023 in the treatment of LN. Compared with that in the Normal group, the mRNA expression of the core target in the SLE and LN groups was different; compared with the MRL/lpr group, the LNP023 treatment group showed different mRNA and protein expression levels of AKT, TNF-α, and STST3. CONCLUSIONS LNP023 improves LN in MRL/lpr mice. The mechanism is as follows: LNP023 binds to CFB to inhibit the activation of the alternative complement pathway. LNP023 treatment for LN may also play a role in regulating the protein expression of AKT, TNF-α, and STST3.