To explore the clinical effect of self-made Maziren Zengye Decoction on patients with constipation predominant irritable bowel syndrome (IBS-C).Methods:A total of 100 IBS-C patients admitted to the Third People's Hospital of Haikou City from February 2017 to February 2019 were selected as the research objects and were randomly divided into a control group (n＝49，lactulose treatment) and an observation group (n＝51，self-made Maziren Zengye decoction+lactulose treatment).The clinical efficacy，TCM symptom score，microecological changes of intestinal microflora，quality of life and adverse reactions between the 2 groups were compared.Results:The total clinical effective rate in the observation group was 94.12%，which was higher than 79.59% in the control group (P<0.05).After treatment，the scores of dry stool，abdominal distension，abdominal pain，hot flashes，red cheeks，dry mouth，little body fluid，short and red urine and body heat in the observation group were lower than those in the control group (P<0.05).After treatment，Lactobacillusm，Bifidobacterium and colonization resistance of intestinal flora B/E value in the observation group were higher than those in the control group，while Bacteroides and Enterobacter in the observation group were lower than those in the control group (P<0.05).After treatment，the scores of health anxiety，anxiety，somatic ideation，social function，interpersonal relationship，pickiness，behavioral disorder and sexual behavior in the observation group were higher than those in the control group (P<0.05).There was no difference in the incidence of adverse reactions between the 2 groups (P>0.05).Conclusion:The self-made Maziren Zengye Decoction has a good therapeutic effect on IBS-C patients.It can adjust the changes of intestinal microflora，improve the micro-ecological environment，and improve the quality of life.