Objective To explore the status of nutrition risk and its relative factors in patients of department of gastrointestinal surgery, and to observe the effectiveness of nutrition support on post-operative recovery of patients with gastric cancer. Methods A total of 1 048 cases of in-patients in Department of Gastrointestinal Surgery of Jinan Central Hospital Affiliated Shandong University from January 2015 to January 2016 were collected prospectively, and then screened the nutrition risk of these patients by nutritional risk screening 2002 (NRS-2002) and evaluated the actual malnutrition situation when they left hospital. Then collected 52 gastric cancer patients whose NRS-2002 score ≥3, and divided them to control group and experimental group randomly. The patients of experimental group received extra standard medical nutrition support while the patients of control group did not. Compared the nutritional indexes as well as some postoperative recovery indexes, such as the postoperative exhaust time, postoperative defecation time, infusion stop time, length of hospital stay, and incidence of complications. Results ① Nutritional risk. Among the 1 048 cases, 230 cases (21.9%) had nutritional risk while 118 cases (11.3%) developed to malnutrition. Age and degree of cancer were all related with nutritional risk (P<0.05) while gender was irrelevant (P>0.05). Patients with age ≥60 years, advanced gastric cancer, and colorectal cancer in Ⅲ+Ⅳ staging, had higher rates of nutritional risk than patients with age <60 years, early gastric cancer, and colorectal cancer inⅠ+Ⅱstaging. Results of actual malnutrition was in good accordance with the screening result of NRS-2002 (κ=0.57). ② Influence of nutritional support on gastric cancer patients. Compared with control group, there was an improvement in albumin, pre-albumin, and weight of experimental group and the distinction had statistical significance (P<0.05). The distinction of postoperative exhaust time and incidence of complication between the two groups were not statistically significant (P>0.05), but postoperative defecation time, infusion stop time, and the length of hospital stay of the experimental group were shorter than those of the control group with statistical significance (P<0.05). Conclusions The problem of malnutrition exists generally in the in-patients of department of gastrointestinal surgery. Applying the instrument of nutritional risk assessment to assess the risk as early as possible and giving appropriate nutrition support therapy positively, will make favorable influence to the prognosis of gastric cancer patients.