Objective：To investigate the effects of nutritional support on clinical outcomes in patients with nutritional risk. Methods：Method of prospective cohort study was adopted. Nutritional risk of patients in the department of gastroenterology and department of gastrointestinal surgery was assessed by applying the nutritional risk screening tool 2002（NRS 2002）. Patients with NRS score ≥3 were divided into two groups by the presence of nutritional support. Clinical data of the two groups were observed and recorded. In－fluence of nutritional support on complications and hospitalization time in patients with nutritional risk were analyzed. Results：Totally 1 490 patients were screened and 440 patients were included in the cohort study，including 186 patients（142.3%） in nutritional sup－port group and 254 patients（57.7%） in non-nutritional support group. Complications were occurred in 70 patients，including 19 patients（10.2%） in nutritional support group and 51 patients（20.1%） in non-nutritional support group，with statistically significant dif－ferences between two groups（P=0.005）. The length of hospital stay was （12.8±3.9） d in nutritional support group and （15.6±6.1） d in non-nutritional support group，with statistically significant differences between two groups（t=5.937，P=0.000）. Logistic regression analysis of patients with infectious complications showed that malnutrition，a serious decline in body weight，nutritional support and acceptance of major abdominal surgery were related with the incidence of infectious complications and nutritional support was a protective factor. Conclusion：Proper nutritional support can reduce the incidence of complications in patients with nutritional risk and shorten the length of hospital stay. Early nutritional risk screening should be conducted. Giving effective nutritional interventions timely to the nutritional-risk patients will be of great significance.