The extreme phase of the disease of novel coronavirus pneumonia is mostly in 9-12 days, which means that 9-12 days is the most dangerous time. The main manifestations of novel coronavirus pneumonia are fever, dry cough, and malaise, accompanied by nasal congestion, runny nose, sore throat, and diarrhea in a few cases. Fever is the first symptom, and most of the patients have low and moderate fever, and patients with persistent high fever are severely ill. Patients with severe disease mostly develop respiratory distress and/or hypoxemia after 1 week, so the disease should be closely observed within 1 week of the onset of the disease to detect severe cases as early as possible. The extreme phase of the disease is in 9-12 days, and the severe cases may progress rapidly to acute respiratory distress syndrome, septic shock, as well as metabolic acidosis and coagulopathy that are difficult to correct.