Objective To systematically review the effects of enteral immunonutrition (EIN) on postoperative infection and the length of hospital stay in patients with gastrointestinal cancer after surgery, in order to provide high quality evidence for the rational perioperation nutrition plan for patients with malignant gastrointestinal tumor. Methods Randomized controlled trials (RCTs) published in English about application of EIN vs. general treatment for gastrointestinal surgery published from Jan. 1st, 1997 to Oct. 31st 2012 were retrieved in the following databases: PubMed, Ovid, and EMbase. References of the included studies were also retrieved. According to the inclusion and exclusion criteria, two reviewers independently screened studies, extracted data, and evaluated the methodological quality. Then, meta-analysis was conducted using RevMan 5.2 software. Results 19 RCTs involving 2 298 patients were included. The results of meta-analysis showed that: there was no significant difference between the postoperative EIN group and the control group in reducing the risk of postoperative infection (OR=0.91, 95%CI 0.56 to 1.47, P=0.70); But postoperative and perioperative EIN had reduced the risk of postoperative infection with a significant difference (OR=0.57, 95%CI 0.39 to 0.82, P=0.002; OR=0.52, 95%CI 0.35 to 0.76, P=0.000 9). Additionally, the results of sensitivity analysis revealed that: no matter when EIN was used (during preoperative, postoperative, or perioperative periods), it reduced the length of postoperative hospital stay with significant differences, compared to the standard nutrition group (OR= −2.39, 95%CI −3.28 to −1.49, Plt;0.000 01; OR= −2.42, 95%CI −4.07 to −0.78, P=0.004; OR= −2.76, 95%CI −3.46 to −2.06, Plt;0.000 01). Conclusion Current evidence shows that perioperative EIN can decrease postoperative infection and reduce the length of hospital stay of patients with malignant gastrointestinal tumor. Due to the limited quantity and quality of the included studies, high quality RCTs are needed to verify the above conclusion.