Postoperative malnutrition is a major issue among gastrointestinal cancer patients. Because n-3 polyunsaturated fatty acids (n-3 PUFAs) have immunological benefits, n-3 PUFAs are widely used in oral nutritional supplements (ONS). However, n-3 PUFAs in ONS reduced patients' compliance with ONS and affected the role of ONS in maintaining the postoperative nutritional status of patients. The aim of this study was to systematically explore the benefits of enteral nutrition rich in n-3 PUFAs in maintaining the nutritional status of patients after gastrointestinal surgery. Databases including PubMed, Web of Science, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang, and VIP databases were searched through March 16, 2019. The references of related reviews and studies were assessed up to March 16, 2019. The effect sizes from individual studies were calculated as the standardized mean difference (SMD), mean difference (MD), and risk ratio (RR) with 95% confidence intervals (95% CIs). A total of 11 studies (n = 977) were included. In this systematic review and meta-analysis, we observed that enteral supplementation of n-3 PUFAs had no significant effect on weight (MD, 1.09; 95% CI, -0.90, 3.08), body mass index (MD, 0.55; 95% CI, -1.45, 2.54), albumin (SMD, 0.39; 95% CI, -0.10, 0.87), wound infections (RR, 0.87, 95% CI, 0.57, 1.33), or pneumonia (RR, 0.98; 95% CI, 0.60, 1.59) in gastrointestinal cancer patients. Thus, compared with enteral nutritional without n-3 PUFAs, enteral nutritional rich in n-3 PUFAs has no significant effects on nutritional status, incidence of pneumonia, or wound infections among gastrointestinal cancer patients during postoperative convalescence.