To investigate the influence of sulfur dioxide (SO₂) on lipopolysaccharide (LPS)-induced acute lung injury (ALI), we examined the influence of exogenous SO₂ on pulmonary tissue inflammatory response. A rat model of ALI induced by intravenous (IV) injection of LPS was developed. Male Sprague-Dawley (SD) rats were divided into four groups randomly: control group, LPS group, LPS plus SO₂ group (IV injection of 0.5 mL Na₂SO₃/NaHSO₃ 10 min before LPS administration) and SO₂ group (only given Na₂SO₃/NaHSO₃). Animals were sacrificed 6 h after agent administration. Lung weight/body weight ratio (LW/BW) was measured and calculated. Morphological changes of lung tissues were observed. The number of polymorphonuclear neutrophil (PMN) in the bronchoalveolar lavage fluid (BALF), intercellular adhesion factor-1 (ICAM-1) expression in the lung tissue and IL-1, IL-6 and IL-10 levels in the serum were tested. The results showed that, compared to control rats, the LPS-treated rats had severe injuries of lung tissues and an increased LW/BW, increased index of quantitative assessment (IQA) score, increased PMN number in the BALF, increased ICAM-1 expression in the lung tissue and increased IL-1, IL-6 and IL-10 levels in the serum 6 h after LPS injection. Administration of the SO₂ donor, Na₂SO/₃NaHSO₃, into LPS-treated rats reduced the LW/BW, PMN number and ICAM-1 expression, and alleviated the degree of ALI (measured by the IQA score). In addition, Na₂SO₃/NaHSO₃ decreased IL-1 and IL-6 levels, but increased IL-10 level in the serum. There were no significant differences in the above indexes between SO₂-treated rats and control rats. These results suggest that exogenous SO₂ could inhibit the pulmonary tissue inflammatory response in rats with LPS-induced ALI.