Abstract: In view of actual operating condition of Daqing-Harbin buried hot oil pipeline, the simplified unsteady state heat transfer physical and mathematical models in shutdown time are established taking the most dangerous pipe section in shutdown as a study object.Making use of CFD software, an ordinary rule of crude oil temperature changing with time are simulated, and the safe shutdown time of Daqing-Harbin pipeline all the year round is confirmed and then theoretical direction for pipeline safety operation is provided.