Objective:To study the duration of invasive mechanical ventilation (MV) and its influencing factors after neonatal abdominal surgery under general anesthesia in neonatal intensive care unit (NICU).Methods:From January 2018 to December 2020, neonates received abdominal surgery under general anesthesia and needed endotracheal intubation and MV after surgery in NICU of our hospital were retrospectively studied. According to MV duration, the neonates were assigned into <72 h group and ≥72 h group. Multivariate logistic regression was used to analyze the risk factors of postoperative MV duration.Results:A total of 113 neonates were enrolled, including 57 male (50.4%) and 56 female (49.6%). The gestational age was (35.7±3.6) weeks, the birth weight was (2 497±933) g, the average operation age was 9.9(3.6, 22.2) d and the average hospital stay was 22.0(12.0,37.0) d. Congenital intestinal obstruction (37/113, 32.7%) was the most common diagnoses on discharge, followed by neonatal necrotizing enterocolitis(28/113,24.8%) and gastrointestinal perforation (18/113,15.0%). The duration of operation was 80.0 (55.8,117.3) min. All neonates needed MV with endotracheal intubation. The duration of postoperative respiratory support was 30.0(7.0,84.5) h. 48 neonates (42.5%) had endotracheal intubation removed within 24 h after surgery. Multivariate logistic regression analysis showed that preoperative respiratory support ( P=0.004), congenital heart disease( P=0.013) and intravenous midazolam ( P=0.032) were independent risk factors for prolonged postoperative MV. Conclusions:The need of preoperative respiratory support, congential heart disease and intravenous midazolam were independent risk factors for the duration of postoperative MV after neonatal abdominal surgery under general anesthesia.