Abstract: A calculation model for economic depth of buried hot oil pipelines using the sum of the apportioned charges per year in pipe ditch excavation investment and that of the thermal loss in pipe operation is given as a object function in this paper, considering the effect of heat transfer coefficient influenced by the buried depth, insulator material, insulator thickness and soil nature. An actual example shows that the buried depth economically is affected obviously by the changeable heat transfer coefficient with varying pipe buried depth, and the model mentioned in this paper not only better reflects the influence in differentaspects, but also avoids the blindness of the heat transfer coefficient, and it can quickly converge as well. This model can provide some theoretical basis for the technological optimal design in the construction of buried hot oil pipelines.