Abstract: According to the heat transfer characteristic of laying buried pipelines in one ditch, the unsteady heat transfer law of crude oil pipeline and products oil pipeline laid in one ditch is numerically simulated by the finite volume method.Calculation analysis on impacting factors such as the distance between crude oil pipeline and products oil pipeline, buried depth and products oil temperature on the heat transfer law of pipeline laid in one ditch has been carried out.The analysis results show that increasing the distance between pipes can effectively decrease the average heat flux of heat dissipation from the wall of crude oil pipeline.When the dis-tance between pipes is bigger to a certain value, the average heat flux of heat dissipation from the wall of crude oil pipeline tends to a saturation state.Increasing the buried depth of pipeline can decrease the average heat flux of heat dissipation from the wall of crude oil pipeline and products oil pipeline, further it can also increase the absorbed heat of products oil and the delay time for pipeline heat transfer coefficient to respond to the change of surface temperature.Increasing products oil temperature can effectively decrease the average heat flux of heat dissipation from the wall of crude oil pipeline.