Objective To investigate the novel coronavirus asymptomatic infection screening and taking time. Methods Throat swab samples were collected from high-risk groups for detection of NCV nucleic acid,and descriptive epidemiological analysis was conducted. Results The novel coronavirus was screened for 1497 cases,and 13 cases were asymptomatic.The positive rate was 0.87%.The positive rate of the close contacts was 2.06%,and the positive rate of overseas returnees was 0.14%.The positive rate of BM screening among the specific population was 0.66%.The positive rate of new coronavirus nucleic acid in three groups was statistically significant (χ²=12.525,P=0.002),and the positive rate of the close contact population was higher than that of the two groups of overseas visitors and BM shopping malls.The shortest time of carrying virus was 9d,the longest was 39d,and the median was 15d.The interval between the last exposure and positive detection was 3 days,the longest was 24 days,and the median was 14 days.The close contacts of 13 asymptomatic patients were negative. Conclusion 13 asymptomatic infections were mainly from close contacts,with a long time of carrying the virus.Most of the cases were found early and isolated early,which did not cause community transmission.