Acute interstitial pneumonia (AIP) is a rapidly deteriorating, fatal respiratory disease of unknown origin. It differs from other types of idiopathic interstitial pneumonia in that: 1) the onset of the disease is rapid; 2) the prodromal symptoms are confusing, resembling a cold, with fever and general malaise, and most are diagnosed early as “upper respiratory tract infection” and given anti-infective treatment, but are ineffective; 3) the deterioration of symptoms (dyspnea) is unimaginably rapid; 4, hypoxia is difficult to correct; 5, the mortality rate is extremely high, the death rate of 1-2 months is more than 50%; 6, the diagnosis is difficult to confirm, most need lung biopsy or autopsy, domestic diagnosis is mostly clinical diagnosis, after excluding other causes, clinically consistent with acute respiratory distress syndrome is considered; 7, low awareness, because it is relatively rare, including medical personnel do not know enough.