We have examined the mechanism underlying amelioration of sepsis-induced acute lung injury by chelidonine in newborn mice. To this end, a sepsis model was established using cecal ligation and puncture in newborn mice. The sepsis-induced acute lung injury was associated with an increased inflammatory infiltration and pulmonary congestion, as well as abnormal alveolar morphology. The lung injury-associated increased tumor necrosis factor-α and interleukin-1β in bronchoalveolar lavage fluid and lung, the markers of inflammatory infiltration and pulmonary congestion, diminished by chelidonine treatment. Chelidonine administration also downregulated protein levels of toll-like receptor 4, myeloid differentiation factor 88, phosphorylated nuclear factor-kappa B, and nuclear factor-kappa B that are elevated in response to sepsis. In conclusion, chelidonine provides a potential therapeutic strategy for newborn mice with acute lung injury.