Abstract: The accurate mathematical model can not be establishecj between the daily oil output and temperature, as well as viscosity due to the changing components of coming oils, which makes it impossible to determine accurately the temperature of the heated oil, or the viscosity of outlet oil heated for the process of heated oil transportation in either controlling temperature or controlling viscosity. Based on stable flow is equiya-leni to stable viscosity, the automatic control system which is constituted with flow sensor, rather than viscosity sensor, is brought on to control the temperature of -heater, thus the process of heated oil trans-portation in controlling viscosity is realized. Because the flow of crude oil can be calculated accurately according to the daily output operational mangement is simplized. If decreased ambient temperature makes viscosity high and flow low of oil in-pipeline during operation, the flow sensor will take action for this and increase the temperature of the heater through the automatic control system to ensure safe and reliable operation. Other advantages from using flow sensor are that design and construction of sampling pipeline and purchase of special flow sensor can be saved.