Objective To investigate the treatment effects of dahuang gancao decoction on lung Injury complicated by acute necrotizing pancreatitis and explore its mechanism. Methods 90 Wistar rats were randomly divided into 3 groups, namely sham-operated group (SO), ANP group (ANP), dahuang gancao decoction treatment group (DG). 4% sodium taurocholate was injected into the pancreatic duct to induce ANP. Dahuang gancao decoction(0.25 g/ml) 0.6 ml/100 g weight was gavaged in the DG group, the same volume of normal saline was gavaged in the SO and ANP group, which was repeated 12 h later. After 6 h, 12 h, 24 h, all rats were sacrificed, pancreas and lung tissues were harvested to observe the pathological changes and the pathological changes were scored. IL-6, IL-10, TNF-α levels of serum and lung tissue were measured,and the changes of toll-like receptor 4 (TLR4) expression in lung tissue was determined by immunohistochemical method. Results 12 h after ANP induction, the serum levels of IL-6 in SO, ANP, DG group were (14.4±4.0)pg/ml, (171.4 ±41.3)pg/ml, (156.9 ±34.7)pg/ml; the serum levels of IL-10 were (13.7 ±4.5)pg/ml, (120.5 ±23.7)pg/ml, (148.3 ±44.4)pg/ml; the serum levels of TNF-α were (22.4 ±4.7)pg/ml, (261.3 ±51.4)pg/ml, (235.3 ±45.9)pg/ml; the lung tissue levels of IL-6 were (257.3 ±55.9)pg/ml,(2578.3 ±403.0)pg/ml,(2370.0 ±491.0)pg/ml; the lung tissue levels of IL-10 were (80.8 ±20. 8)pg/g, (642.0 ± 107.3)pg/g, (695.3 ± 151.7) pg/g, the lung tissue levels of TNF-α were (207.6 ±98.6)pg/g, (1769.1 ±635.6) pg/g, (1401.1 ±450.5) pg/g; the pancreas pathological scores were 0, 7.00 ±1.33, 6.30 ± 0.95; the lung pathological scores were 0, 6.30 ± 1.42, 5.60 ± 0.97; the expressions of TLR4in lung tissue were 0.09 ± 0. 03, 0.59 ± 0. 09, 0. 52 ± 0. 08. The values in the ANP and DG groups were significantly higher than those in SO group (P < 0. 01 ); except for IL-10, all values in the DG groups were significantly lower than those in ANP group (P < 0.05); there was a positive association between lung and pancreas scores (r =0.807, P<0.01), and lung score was positively associated with the expression of TLR4(r = 0.519, P < 0.01 ). Conclusions Dahuang ganeao decoction may quickly improve lung injury complivated by ANP. The mechanism may involve inhibiting the expression of TLR4 and down-regulating the expression of IL-6, TNF-α, up-regulating the. Expression of IL-10.