Objective To analyze the role of lienal polypeptide injection in acute lung injury induced by lipopolysaccharide (LPS) in rats. Methods Eighty male SD rats were randomly allocated into 4 groups: a LPS group, a control group, a lienal polypeptide group and a LPS+ lienal polypeptide group (20 rats in each group). Lienal polypeptide or normal saline was given with an intramuscular injection 30 min after an intraperitoneal injection of LPS (5 mg/kg). The severity of pulmonary injury was evaluated 4 h after LPS challenge by enzyme-linked immunosorbent assay (ELISA), wet-to-dry weight ratio, hematoxylin and eosin (HE) staining, TUNEL and Western blotting. Results Lienal polypeptide injection treatment significantly attenuated LPS-induced pulmonary histopathologic changes, alveolar hemorrhage, and neutrophil infiltration. Moreover lienal polypeptide injection significantly suppressed LPS-induced activation of metastasis-associated protein-1 (MTA1). Conclusion Lienal polypeptide injection is demonstrated to protect rats from LPS-induced acute lung injury by the expression of MTA1.