The newly imported asymptomatic infected person was a 44 year old Philippine crew member of the Fontana tanker. On August 27, the fangtana oil tanker arrived at the port of Changxing Island, Dalian. On August 28, the customs went through the customs entry. On August 29, Dalian Changxing Island customs implemented boarding quarantine on the ship, and its nucleic acid was weakly positive. On August 30, the customs conducted nucleic acid test again, and the result was positive. On the same day, the nucleic acid was positive by Dalian Center for Disease Control and prevention. In August 31st, novel coronavirus pneumonia was transferred to Dalian Center for quarantine observation. A novel coronavirus asymptomatic infection was diagnosed by the municipal expert group in September 1st. Closed loop management was adopted after the patient entered the country.