Objective To assess the short-time economics of various glutamine dipeptide-enriched parenteral nutrition (PN) for patients undergoing elective surgery for gastrointestinal tumors, with an attempt to provide evidence for decision makers on clinical nutrition support.Methods A prospective cohort study was designed.From payer/disburser''s perspective, a cost-effectiveness decision-tree model was developed to assess the clinical outcomes and short-time economic effects of glutamine dipeptide-enriched PN that used in different time points (early postoperative or perioperative).Cost-effectiveness analysis, cost-utility analysis, and incremental cost-effectiveness analysis were adopted in the decision-tree model.One-way sensitivity analysis was performed to determine the robustness of the results.Results Totally 107 patients were included.There was no significant difference between the perioperative alanine(Ala) glutamine(Gln) nutrition support (group A) and early postoperative Ala-Gln nutrition support (group B) in the ratio of 5％ weight declines on the 8th day after surgery and infection-related postoperative complications (72.1％ vs.78.1％, χ2=0.509, P=0.498 and 2.32％ vs.4.69％, χ2=0.060, P=0.806).The levels of prealbumin (PA) and albumin(Alb) and the level of total lymphocyte count(TLC) also the time of recovering gastrointestinal function, length of stay nutritional discharge index(LOSNDI), and direct costs were significantly different [PA:(208.19±56.92)mg/L vs.(187.97±62.05)mg/L, t=2.283,P=0.039;Alb:(33.82±3.91)×109 vs.(31.96±4.57)×109, t=2.184, P=0.036;TLC:(1.19±0.55)×109 vs.(0.89±0.66)×109, t=2.461, P=0.015;the time of recovering gastrointestinal function(3.06±0.28)d vs.(3.39 ± 0.34)d, t=-3.675, P=0.000;LOSNDI:(16.84±2.92)d vs.(18.52 ±3.47)d, t=-2.613, P=0.011;direct costs:￥(17 029.05±317.28) vs.￥(15 610.64±292.56), t=23.764, P=0.000].When LOSNDI and quality-adjusted life years (QALYs) were estimated as indicators of effectiveness, the incremental cost-effectiveness ratios and incremental cost-utility ratios of group A were ￥844.3 and ￥70 920.5, respectively.Net monetary benefit of group B was more than that of group A.One-way sensitivity analysis showed that parameters had no significant effect on the model.Conclusion When using local per capita gross domestic product as threshold, early postoperative Ala-Gln PN was more economical than perioperative Ala-Gln PN strategy evaluation.