The main methods of detection of novel coronavirus are nucleic acid testing and viral gene sequencing, but viral gene sequencing is not commonly used, and nucleic acid testing is currently the most commonly used clinical test, which can be performed using nasopharyngeal swabs, sputum, lower respiratory secretions, stool and blood as specimens. If nucleic acid is detected, the diagnosis of novel coronavirus infection can be confirmed. If the nucleic acid test is repeatedly negative, but the patient has an epidemiological history, and the clinical symptoms are consistent, the blood count is consistent with a decrease in lymphocyte count, and the lung CT is also consistent with the diagnostic imaging criteria of lung CT of novel coronavirus, the patient can also be diagnosed as a suspected case through clinical manifestations, and the suspected case should be treated in isolation in a single room.