Abstract: The discrete method based on equal temperature-drop step increment for heat oil pipeline's process computing is outlined in the paper. The method could conveniently be utilized to dispose the changing situation such as flow condition and physical behavior change taken place during transportation due to varying oil temperature. The step length could be adjustable, which keeps the temperature of the physical behavior point at calculating point all the time and the function relationship between oil physical behaviorparameters and temperature is discontinuous more accurate and easy.The iterative formula utilized to calculate friction thermal influence is also given out, which is simple than discrete progress. Automatically selecting the method for step length calculation according to flow capacity, oil temperature and burying condition improves calculating speed and precision.