The cause of novel coronavirus is mainly the invasion of novel coronavirus into the human body through respiratory flight transmission, contact transmission, and fecal-oral route transmission. Some of the novel coronaviruses can be cleared by the human immune system, but some of them invade normal cells through the protein shell of the virus itself and replicate and disseminate in large numbers in the body, leading to a series of clinical manifestations. Therefore, elderly people with low immunity and patients with underlying diseases are more susceptible to infection and often have more severe disease. The main clinical manifestations are fever, malaise, dry cough and other respiratory symptoms, and some manifest digestive symptoms such as diarrhea. In severe cases, acute respiratory distress syndrome may occur, and patients may have severe respiratory failure, so timely treatment is required.