Abstract: The influence of heating temperature, temperature increment during heating, and volatilization of light component in heating of Sudanese oil with the flow improver added on the treating effectiveness has been researched. The result shows that for the high condensation point and highly-viscous Sudanese crude oil, the oil viscosity is decreased greatly as the heating temperature is increased. The temperature's backstepping will limit the modified result of drug during the oil heating. The modification result will be good when the water cut of crude is reduced. The volatilization of light component of crude is one of the important factors influencing the modification effectiveness in the non-tight heating vessel, especially during the slow temperature drop.