To compare the prognosis of elderly patients with gastric and colorectal cancer treated with different nutritional support methods. Elderly patients with gastrointestinal tumors who received surgical treatment in Beijing Hospital from January 2019 to June 2020 were retrospectively included and divided into malnourished group and non-malnourished group according to the Global Leadership Initiative on Malnutrition (GLIM). The patients were divided into parenteral nutrition (PN) group, enteral nutrition (EN) group and enteral+parenteral nutrition (EN+PN) group according to the nutritional support. The prognosis of patients with different nutritional support treatment was compared. A total of 426 elderly patients with gastric and colorectal tumors underwent surgical treatment were included, including 287 males and 139 females, aged 65-91 (72±6) years. There were 186 cases in malnourished group and 240 cases in non-malnourished group. A total of 257 patients received nutritional support therapy, including 108 cases in PN group, 48 cases in EN group and 101 cases in EN+PN group. The body mass index (BMI) of malnutrition group was lower than that of non-malnutrition group [(20.5±3.4) vs (23.7±2.8) kg/m, <0.001], and the score of nutritional risk screening 2002 (NRS 2002) [ (, )] was higher than that of non-malnutrition group [4 (4, 5) vs 2 (2, 3) points, <0.001]. The total hospitalization time of patients in EN group was shorter than that in PN group and EN+PN group [(11.9±4.0) vs (16.5±6.5) and (19.2±7.1) d, all <0.001]. The total hospitalization time in PN group was shorter than that in EN+PN group [(16.5±6.5) vs (19.2±7.1) d, =0.005]. The total incidence of complications in EN group was lower than that in PN group [0 vs 9.3% (10/108), =0.030] and EN+PN group [0 vs 19.8% (20/101), <0.001]. The incidence of total complications in PN group was lower than that in EN+PN group [9.3% (10/108) vs 19.8% (20/101), =0.030]. Among the three nutritional supportive treatment modalities: EN, PN, and EN+PN, patients receiving EN support treatment have a shorter total hospitalization time and a lower complication rate.