Abstract: Objective: To investigate the protective effects of interleukin-10 on ALI. Methods: A rat model of ALI was induced by intratracheal instillation of LPS with a dose of 10mg/kg. 54 male S-D rats were randomly divided into control group、LPS group and LPS+IL-10 group,every group included 18 rats（6 rats at 2 hours、6hours and 24hours respectively）.the body weight of rat、arterial gas analysis、the lung coefficient、the total protein concentration in BALF、the total cell counts and classification in BALF、the level of TNF-αin serum and BALF、lung pathology were examined. Results: In LPS group the body weight and PaO₂ were progressively decreased, the lung coefficient、the total protein concentration in BALF、the total cell count in BALF、 the level of TNF-αin serum and BALF were greatly increased, lung pathology showed severe polymorphonuclear leukocytes infiltration with bleeding and hyaline membranes. Conclusion: ①Intratracheal instillation of LPS may serve as a very relevant model to study ALI. ②TNF-α in BALF may has more significance than TNF-α in serum on assessment of lung injury. ③IL-10 could relieve ALI of rats.