Abstract: Objective:To observe therapy effect of ω-3 polyunsaturated fatty acids in severe brain injury complicated by lung infection. Methods:Fifty-six cases of severe brain injury in patients with pulmonary infection were randomly divided into control group and Ewing group. Before division, all the patients were given the relevant examination and treatments such as antibiotics, reducing intracranial pressure,as well as endotracheal intubation, ventilator application and post-tracheotomy. Both groups were given energy supplement 105~125 kJ·kg^-1·d^-1,but in Ewing group,some of the heat were provided by the fat emulsion of ω-3 fatty acids. On the 0th,2nd,4th and 7th day patients'maximum day temperature,respiratory rate,heart rate,white blood cell,oxygenation index were monitored,and finally prognosis,ICU stay time,ventilation time and an average cost of the two groups of patients during ICU stay time were recorded. Results:The control group and Ewing group with positive anti-infection treatments are getting better. Clinical indicators of Ewing group and the control group on the 2nd day were not statistically significant(P>0.05). The vital signs(temperature,heart rate,respiration) and white blood cells of the two groups of patients showed downward trend over time,while the oxygenation index showed an upward trend over time,which is more significant for Ewing group on the 4th and 7th day compared with the control group, and the difference was statistically significant(P<0.05-P<0.01). After the 7-day observation in the prognosis outcome,the two groups showed no significant differences,not statistically significant(P>0.05). However,in the average ventilator time,ICU length of stay and cost,the two groups has significant differences,with statistical significance(P<0.01). Conclusions:ω-3 polyunsaturated fatty acids on severe brain injury in patients with pulmonary infection in the body has a protective effect.