Objective To probe into the application of portable ventilator in critically ill patients in prehospital. Methods 100 patients with critically ill and who were treated with cardiopulmonary resuscitation in our hospital from August, 2005 to December, 2014 were taken as the research objects, and these patients were randomly divided into the control group and the study group according to first aid (patients and patients' families were aware of the treatment plan, and signed confirmation), with 50 patients in each group. In the control group, they were given the artificial balloon assisted respiration while in the study group, they were treated with the portable ventilator. Then, the rescue status and vital signs index of two groups of patients were compared. Results The success rate of cardiopulmonary resuscitation in two groups were compared while in the research group of 34% was significantly higher than that in the control group of 10%, and the data had statistically significant (P<0.05). In addition, the index of every sign in the rescue process of two groups of patients were compared including SPO2, SBP, DBP, HR and other aspects, which in the study group was significantly better than those in the control group, and the data had statistically significant (P<0.05). Conclusion The portable ventilator can be used in critically ill patients in prehospital which this method can improve the success rate of cardiopulmonary resuscitation, and improve the vital signs index of patients.