Objective To study the analgesia effects and possible mechanism of Dajianzhong Decoction（ 大建中汤） on rats with chronic inflammatory visceral pain. Methods A total of 40 SD rats were randomly divided into normal group

model group

acetaminophen group and Dajianzhong Decoction group

with 10 rats in each group. Except the normal group

the other 3 groups were clystered by 5% trinitrobenzene sulfonic acid（ TNBS） in preparing the model of chronic inflammatory visceral pain rat. Dajingzhong Decoction（ 0. 22 g/kg·d） was given to the Dajingzhong Decoction group since the second day after the modeling. The acetaminophen solution（ 0. 002 g/kg·d） was given to the acetaminophen group by gavage. The saline solution（ 7 ml/kg·d） was given to the normal group and the model group by gavage. The intervention for all groups last for 14 days continuously. The general conditions and body weight of the rats were recorded. The abdominal withdrawal reflex（ AWR） score was performed under the pressure of20 mm Hg

40 mm Hg

60 mm Hg

and 80 mm Hg after the experiment. The content of tumor necrosis factor α（ TNF-α） and interleukin-6（ IL-6） in serum

interleuk-1 receptor-associated kinase 4（ IRAK-4） mRNA expression on colonic mucosa was detected at the same time. The pathologic features of colonic mucosa were observed by HE staining.Results Compared with the normal group

the body weight of rates in model group was decreased and the AWR score was significantly increased under each kind of pressures（ P < 0. 01）. The pathological damage of the colonic mucosa was more obvious

and the levels of serum IL-6

TNF-α and the expression of IRAK-4 mRNA were significantly increased（ P < 0. 01）. Compared with the model group

the body weight of rates in acetaminophen group and Dajianzhong Decoction group were increased and the AWR score were decreased under each kind of pressures（ P <0. 05）. The pathological states of colonic mucosa were improved

and the content of serum IL-6

TNF-α and the expression of IRAK-4 mRNA in intestinal tissue was significantly decreased（ P < 0. 01）. Conclusion Dajianzhong Decoction has significant analgesic effects on rats with colon mucosa of chronic inflammatory visceral pain

and the possible mechanism might concerns with the decreasing of IL-6

TNF-α in serum and the expression of IRAK-4.