To observe the clinical efficacy of Zhuyang Tongbian Decoction（助阳通便汤）on patients with functional constipation（spleen and kidney Yang deficiency）and the effects of serum substance P（SP）and vasoactive intestinal peptide（VIP）as well as its effects on the histopathology of the colon and the expression of VIPin the constipation model mice.

（1）Sixty-six patients who met the diagnosis of functional constipation and whose TCM syndrome was spleen and kidney Yang deficiency were grouped by randomized numerical table method，including the treatment group（33 cases）and the control group（33 cases）. The treatment group was given Zhuyang Tongbian Decoction（130 mL）orally twice a day，and the control group was given Lactulose（15 mL）orally twice a day. Both groups were treated for 2 weeks. The constipation symptom scores，fecal character score，traditional Chinese medicine symptom scores and contents of serum SPand VIPbefore and after the use of drugs in the two groups were compared.（2）Eighteen BALB/c mice were divided into KB group（blank control group），MX group（model group）and ZY group（Zhuyang Tongbian Decoction group）according to the randomized numerical table method，6 mice in each group were modeled by gavage with 80 mg/kg of diphenoxylate tablets suspension，and ZY group was given Zhuyang Tongbian Decoction（0.2 mL/10 g）for two weeks，and then samples were taken out to observe the histopathology of colon and VIP immunohistochemical expressions of each group. Colonic histopathology and VIPimmunohistochemical expressions were observed in each group.

（1）The scores of constipation symptoms and fecal character of patients in both groups after treatment were significantly higher than those before treatment（P<0.05）. There was a significant difference in TCM symptom scores in the treatment group（P<0.05）. The serum SP content of patients in the treatment group was higher than that of the control group（P<0.05），and the serum VIPcontent was lower than that of the control group（P<0.05）. The effective rate was 90.0% in the treatment group and 73.3% in the control group（P<0.05）.（2）Compared with the mice in the model group（MX group），the distribution of VIP-positively expressing cells was relatively denser and the number of positive cells was higher in the colonic tissues of the mice in the ZY group（P<0.05）.

The clinical symptoms and traditional Chinese medicine symptoms of patients with functional constipation（spleen and kidney Yang deficiency）were improved by Zhuyang Tongbian Decoction，and it also had an intervention effect on the contents of serum SPand VIPof the patients. The modulation of VIPcontent in the colon tissue of mice with constipation by Zhuyang Tongbian Decoction is one of its mechanisms of action in the treatment of functional constipation.