Objective:To investigate the efcacy and safety of Non-mechanical bowel preparation in patients undergoing surgery of gynaecological malignant tumour.Methods: Patients (n=105) were randomized to receive mechanical bowel preparation（MBP）or Non-mechanical bowel preparation (Non-MBP). The primary outcomes were postoperative gastrointestinal function. Secondary outcomes included Postoperative complaints and plasma of D-lactate and diamine oxidase(DAO). Visualisation of the surgical field, involuntary defecation during surgery, operation time, wound healing, surgical site infection, length of hospital stay, andtolerance of mechanical bowel preparation.Results: Participants in the Non-MBP group exhibited shorter times until first bowel movement (27.87 vs. 29.48 h), first passage of flatus (50.96 vs. 55.08 h), and first passage of stool (75.94 vs. 98.50 h);they also exhibited fewer postoperative gastrointestinal symptoms, including nausea (18.9% vs. 38.5%), vomiting (26.4% vs. 51.9%), abdominal pain (34.0% vs. 78.9%), and bloating (3.8% vs.26.9%). The plasma D-lactate and DAO were significantly increased (2.93 vs. 5.68 nmol/mL and 20.46 vs. 54.49 ng/mL) after bowel preparation in the MBP group; but no differences in the Non-MBP group after bowel preparation. Compared with the MBP group, surgical field visualisation was superior (92.45% vs. 78.85%), and the operation time was shorter (173.58 vs. 203.88 min) in the Non-MBP group. Patients undergoing MBP complained of bloating (82.35%), unpleasant taste (78.43%), sleep disturbance (70.59%), nausea (68.63%), abdominal pain (64.71%), vomiting(45.10%), polydipsia (33.33%), dizziness (25.49%), and headache (7.84%).Conclusions: Non-MBP is more conducive to the recovery of postoperative gastrointestinal function after surgery of gynaecological malignant tumour.Trial registration number: Chictr.org.cn.( ChiCTR2200059101).