Abstract: At present,in the development of heavy oil block,in addition exploited by thermal,but also widely used in the technology of blending light oil.As the situation of exploration and development is becoming increasingly serious,the well has been a great problem of blending light oil.With the increase of blending oil,blending oil costs remain high.To bring unnecessary trouble of production management,at the same time,the serious influence the oilfield development and economic benefits.This paper base on XiaoWa oilfield,and applying the mathematical model of temperature distribution in wellbore,and considering water and sand and other influence factors to single well blending oil,to determine the reasonable temperature and the amount of blending oil.A method for reducing the amount of oil back-blending on the ground in the development of heavy oil block is found by theoretical research and field test.In order to guarantee the normal production of oil field,and efficiency reduce cost,and provide reference basis on the class work for other oilfield.