Objective To study the role of partial pressure of oxygen in the treatment of pulmonary hypertension induced by meconium aspiration syndrome. Methods Retrospective analysis was performed on 58 patients with meconium aspirate and pulmonary hypertension from January 1,2007 to December 31,2016, 28 patients in the death group,and 30 patients in the survival group. Blood gas analysis about two groups of children with mechanical ventilation were collected at four different time points:before mechanical ventilation ( 0 h) ,12 hours after mechanical ventilation,24 hours after mechanical ventilation and 72 hours after mechan-ical ventilation. The 80 mmHg(1 mmHg=0. 133 kPa) in blood gas analysis of the partial pressure of oxygen was used as the boundary point to study the effects about different blood oxygen partial pressures on the length of mechanical ventilation time in the survival group. Results Blood gas analysis showed that there were no significant differences in pH,partial pressure of oxygen,HCO3-,and lactic acid before mechanical ventilation in the two groups,but the pH values were significantly higher in the survival group after 12 h, 24 h,and 72 h of mechanical ventilation(t values:-2. 07,-3. 48,-7. 11;P <0. 05). Partial pressure of oxygen were higher in the surviving group at 12 h,24 h,and 72 h than those in the death group(t values-2. 87,-4. 88,-11. 29; P<0. 05). The HCO3-values of the survival group at 12 h,24 h and 72 h were higher than the death group, and the differences were statistically significant ( t values: -3. 90, -5. 60,-5. 76,P<0. 001). The lactic acid of survival group was significantly lower than the death group at 72 h after ventilation (t=5. 12,P<0. 001). Compared with the death group,partial pressure of carbon dioxide in 24 h,72 h decreased significantly in the surviving group(t values:5. 67,7. 60;P<0. 05). In the surviving group,the partial pressure of oxygen was maintained above 80 mmHg in 18 patients and the mechanical venti-lation time was (7. 17 ± 1. 95) d. The partial pressure of oxygen was below 80 mmHg in 12 patients of the surviving group and the mechanical ventilation time was (8. 67 ± 2. 50)d. The difference was statistically sig-nificant(t =12. 02,P <0. 001). Conclusion In the treatment of newborn with pulmonary hypertension caused by meconium aspiration,maintaining a higher pH value and a partial pressure of oxygen higher than 80 mmHg may be beneficial to the recovery of children with pulmonary hypertension.