Based on the analysis of the lithology of the Lower Permian Shanxi Formation and Benxi Formation reservoirs in the Upper Paleozoic of the Yulin gas field. The influence of sea water temperature and seepage flow rate on the hot oil pipeline unsteady heat transfer is analyzed, the results show that: the relatively greater the see water seepage flow rate is; the longer the radius of the thermal effect in the seepage flow direction of soil temperature field around the pipeline, the shorter the radius of thermal effect vertical to the seepage flow direction, and with the flow velocity increases, the average temperature throughout the soil region increased, the time of the soil temperature to stabilize decreased.