Objective: This study aimed to develop and evaluate a multi-stage optimisation strategy based on the thirst management model to alleviate perioperative thirst and dry mouth symptoms in patients with gastrointestinal cancer. Methods: A total of 132 patients undergoing gastrointestinal tumour surgery were enrolled and divided into an intervention group and a control group based on surgical duration, with 66 patients in each group. The intervention group received a multi-stage thirst management programme based on the Total Modular Management (TMM) approach; the control group received conventional perioperative thirst care. Thirst status, thirst intensity, and lip and tongue mucosal moisture levels were measured at six time points: preoperatively, and at 2 hours, 6 hours, 1 day, 3 days, and 5 days postoperatively. Results: A total of 132 gastrointestinal cancer patients were recruited (66 in each intervention and control group). The intervention group exhibited statistically significant reductions in thirst intensity and thirst-related discomfort scores at time points T1 to T4, alongside statistically significant improvements in oral mucosal moisture scores from T2 to T5. Conclusion: This clinical trial demonstrates that, compared with conventional nursing approaches, a multi-stage thirst management protocol based on the TMM model effectively reduces thirst intensity, alleviates thirst-related discomfort, and improves oral mucosal moisture levels. Trial and Protocol Registration This study underwent supplementary registration with the China Clinical Trial Registry on 9 March 2026, bearing the registration number ChiCTR2600120065.