The use of lung-protective ventilation strategies with low tidal volumes may reduce the occurrence of postoperative pulmonary complications. However, evidence of the association of intraoperative tidal volume settings with pulmonary complications in pediatric patients undergoing major spinal surgery is insufficient. This study examined whether postoperative pulmonary complications were related to tidal volume in this population and, if so, what factors affected the association. In this retrospective cohort study, data from pediatric patients (<18 years old) who underwent posterior spinal fusion between 2016 and 2018 were collected from the hospital electronic medical record. The associations between tidal volume and the clinical outcomes were examined by multivariate logistic regression and stratified analysis. Postoperative pulmonary complications occurred in 41 (16.1%) of 254 patients who met the inclusion criteria. For the entire cohort, tidal volume was associated with an elevated risk of pulmonary complications (adjusted odds ratio [OR] per 1 mL/kg ideal body weight [IBW] increase in tidal volume, 1.28; 95% confidence interval [CI], 1.01-1.63, P = .038). In subgroup analysis, tidal volume was associated with an increased risk of pulmonary complications in patients older than 3 years (adjusted OR per 1 mL/kg IBW increase in tidal volume, 1.43, 95% CI: 1.12-1.84), but not in patients aged 3 years or younger (adjusted OR, 0.78, 95% CI: 0.46-1.35), indicating a significant age interaction (P = .035). In pediatric patients undergoing major spinal surgery, high tidal volume was associated with an elevated risk of postoperative pulmonary complications. However, the effect of tidal volume on pulmonary outcomes in the young subgroup (≤3 years) differed from that in the old (>3 years). Such information may help to optimize ventilation strategy for children of different ages. © 2020 John Wiley & Sons Ltd.