Abstract: The heating cost for hot oil pipeline covers a big proportion for the total energy consumption of pipeline. For the hot oil pipeline, the oil burnt to heat the oil to be transported approximatly takes up 1%-3% of total volume of oil to be transported. For the operation of pipeline, reducing thermal energy loss to cut down the total energy consumption is very important so as to make the transfer cost minimized and increase transfer benefit. Taken Tieling-Dalian oil pipeline as an example, the operation condition of thermal system at low throughput of pipeline has been analyzed, the major factors to influnence the optimal operation of thermal system are exposed, and suggestions to eliminate the factors are presented.