On March 7th, a student from Jilin Agricultural Science and Technology College appeared in the epidemiological data released by Jilin Provincial Health and Health Commission. In the following four days, 68 cases of COVID-19 infection were detected among their close contacts, including 48 asymptomatic infected persons and 20 confirmed patients. This is undoubtedly a major mistake for the current epidemic prevention and control. Previously, in the national nucleic acid on March 4, Jilin Agricultural Science and Technology College had suspected patients taken away by ambulances. With the diagnosis of the case, the school began to close the building on March 5, which not only failed to prevent cross-infection, but also brought about a greater gathering due to apartment conditions and various measures, and then a cluster epidemic occurred.