Objective：To investigate the effects of low flow oxygen-driven nebulization on end-expiratory impedance and vital signs in patients with severe craniocerebral injury after tracheotomy. Methods：We recruited 47 patients with severe craniocerebral injury who underwent tracheotomy and were not mechanically ventilated in our hospital from January 2019 to September 2019. 23 patients from January to April 2019 were the control group and were given oxygen driven nebulization with high flow rate of 6-8 L/min. 24 patients from May to September 2019were the experimental group and were given nebulization with low flow rate of 4-6 L/min. Electrical impedance imaging was used to monitor the changes of end-expiratory lung impedance during the process of nebulization and record the changes of heart rate，percutaneous oxygen saturation and mean arterial blood pressure before and after nebulization in the two groups. The sputum viscosity before and after nebulization were compared between the two groups. Results：There were no significant differences in oxygen saturation and mean arterial blood pressure between the two groups （P>0.05）. The change of heart rate before and after nebulization was less in the lower oxygen flow group than the higher flow group and the difference was statistically significant（P<0.05）. The sputum viscosity of the lower flow group decreased more than the higher flow group and the difference was statistically significant（P<0.05）.End-expiratory lung impedance at 10 minutes of nebulization and 15 minutes after nebulization increased in the lower flow group and the differences were statistically significant（P<0.05）.Conclusion：Low oxygen flow rate（4-6L/min）can be used for oxygen-driven nebulization in patients with severe craniocerebral injury after tracheotomy.