Abstract: Temperature averaging method is often used in China for the process calculations of long distance, hot oil pipeline, with fixed k value, the overall coefficient of heat transfer for the whole line. This method, suffering from low calculating accuracy, results in great deviation from the actuals. The paper introduces a method applicable for hydraulic and thermodynamic calculations for long distance, hot oil pipeline, which is developed based on section-by-section calculation. Taking as variables such parameters as the density.viscosity and heat capacity of the product transported, thermal conductivity factor of the soil, and the overall coefficient of heat transfer, k, this calculation method uses different formula depending on the flow regime and physical properties in different pipeline sections, with the effect of frictional heat on temperature drop taken into account. Comparing with the conventional one, this method enjoys the following advantages: high calculating accuracy and speed, and better applicability for equipment selection and project optimization.