Abstract: Objective To compare the effects of parenteral and enteral nutrition support therapy on the nutritional status and quality of life of the patients with diarrhea predominant irritable bowel syndrome. Methods A total of 160 cases of diarrhea predominant irritable bowel syndrome (IBS-D) in the Fourth Hospital Affiliated to Harbin Medical University from March 2015 to January 2018 were randomly divided into control group and observation group by random digital table, with 80 cases in each group. The control group received routine parenteral nutrition support, while the observation group took parenteral nutrition and enteral nutrition support. The clinical efficacy of the two groups, the changes of nutritional indexes before and after the treatment and the quality of life of the patients were observed and compared. Results The total effective rate in the observation group was 91.2%, which was higher than that in the control group (80.0%), the difference was statistically significant (P<0.05); Before the treatment, the levels of serum albumin, prealbumin and hemoglobin between the two groups were no statistical significance (all P>0.05); after the treatment, the levels of serum albumin, prealbumin and hemoglobin in the observation group were higher than those in the control group, the difference was statistically significant (all P<0.05). Before the treatment, there were no statistical significance between the two groups in the daily social, emotional and mental state, and the energy of patients (all P>0.05); however, after the treatment, the daily social, emotional and mental state, and the energy of patients were improved obviously as compared with the control group, the difference was statistical significance (all P<0.05). The incidence of complications in the observation group was lower than that of the control group, and the difference was statistically significant (P<0.05). Conclusion Nutritional support therapy has significant effect on nutritional status and quality of life in patients with diarrhea predominant irritable bowel syndrome, and enteral nutrition is more effective as compared with the parenteral nutrition support. It can improve nutritional indicators and quality of life of patients, reduce the incidence of complications, and is worthy of clinical promotion.