Abstract: In view of characteristics of large discharge capacity, wide application and convenient management of electrical submersible pumping (ESP), combining with poor lifting efficiency and low wellbore flowing in deep heavy oil reservoir, the technology for blending light hydrocarbon above pump in tubing?casing annular space in ESP wells is studied. The influences of the thermolysis of submersible motor, cable and parameters of blending light hydrocarbon are comprehensively considered. According to the law of the conservation of heat energy, a temperature calculation model for blending light hydrocarbon above pump in tubing?casing annular space in ESP wells is developed.The influences of temperature and volume of blending light hydrocarbon and diluting depth on the temperature distribution of wellbore mixed fluid are analyzed. The study shows that with increasing of temperature of blending light hydrocarbon, the temperature of output fluid closed to the wellhead increases, it is favorable for surface transportation of crude oil. With increasing of the volume of blending light hydrocarbon, the temperature of output fluid closed to the wellhead increases, while that of closing to diluting depth decreases slightly. Output fluid temperature also decreases slightly with the addition of diluting depth, but almost maintains from diluting depth to wellhead. This study has important values of theory and application for optimization of such lifting technology parameters