Abstract: Taking the tight line gathering pipeline of heavy oil blended with 0^# diesel oil as a research object, a mathematical model is established to optimize the variables in the pipeline's total operation cost and analyze the effect of 0^# diesel oil ratio on the pipeline's total operation cost. After adding 0^# diesel oil into heavy oil, friction loss in pipeline decreases, therefore the pump lift needed and electricity consumption are reduced. At set inlet and outlet oil temperatures, factors affecting the total cost of heavy oil pipeline include raw stock cost of 0^# diesel oil which plays a decisive role in the total cost, and electricity charge of pumps. This paper, taking the pipeline of heavy oil mixed with 0^# diesel oil as an example, calculates the operation conditions and total cost at different 0^# diesel oil ratio, and figures out the economical oil transport plan through comparison.