Objective To study the effect of positive pressure ventilation extubation on arterial blood gas indexes of patients undergoing cardiac surgery. Methods 50 patients with orotracheal intubation after intracardiac opening operation under direct vision were randomly divided into the control group and the experimental group with 25 cases in each group. We used traditional method to pull out tracheal intubation in the control group. And positive pressure ventilation at 5 ～15 cm H2O during inspiration and pulling out tracheal intubation during expiration in the experimental group. The change of arterial blood PaO2, PaCO2, SaO2, pH and respiratory rate before and 1min、5min、10min after extubation was observed,and also the incidence rate of air tube obstruction was recorded. Results The change amplitude of arterial blood gas indexes of patients in the experimental group was obviously lower,and the length of change time reduced more than 50%. There were 4 air tube obstructions in the control group and there was no obstruction in the experimental group. The difference was statistically significant. Conclusions Positive pressure ventilation extubation can raise lung's compliance and improve oxygenation. And arterial blood gas indexes are more stable. It can decrease the incidence rate of hypoxemia and is a much more safe method.