Abstract: OBJECTIVE To observe the effects of Yunpi Rougan Fang on serum and colon tissue serum serotonin（5-HT）， vasoactive peptide（VIP） and substance P（SP) in constipation-predominant irritable bowel syndrome rats， to explore its possible mechanism and relevance. METHODS 42 SPF Wistar rats， Six rats were randomly selected as normal group，the remaining 36 rats were modeled by ice water for 14 d，evaluation model， 30 rats were randomly selected and randomly divided into Chinese medicine high， medium and low dose group， western medicine group， model control group， each group had 6 rats. The Chinese medicine low， middle and high dose groups were treated with 12.2， 24.4， 48.8 g/（kg·d)， Mosapride group with moxapril suspension 1.35 mg/（kg·d) gavage，model control group and blank group were given equal amount of distilled water to fill the stomach.After 14 d， the levels of 5-HT， VIP and SP in the serum and the levels of 5-HT and VIP in the colon tissue were measured. RESULTS Compared with the blank group， the expression of 5-HT and VIP in serum and colon tissue immunization in the model control group was increased significantly（P<0.01），the expression of SP in serum was decreased （P<0.05）.Different doses can decrease the levels of serum 5-HT and VIP in C-IBS model rats (P<0.01)， significantly increased the serum SP level (P<0.05). Immunohistochemical results showed that the expression of 5-HT in colon tissue was significantly decreased (P<0.05)， and the expression of VIP was significantly decreased (P<0.01). Although the expression of each treatment group no significant difference (P>0.05)， from the numerical changes， Yunpi Rougan Fang was superior to mosapride and showed dose-dependency. CONCLUSION Yunpi Rougan Fang can obviously improve the symptoms of constipation in C-IBS model rats， by reducing the expression of 5-HT and VIP， improving the expression of SP to regulate intestinal function， which plays a therapeutic role in C-IBS.