Abstract: In order to solve the problems of thermal production of heavy oil by horizontal wells in Chunguang oilfield,such as high viscosity of crude oil,thin separation layer,complex outflowing law and inadaptability of conventional water locating in heavy oil thermal production with horizontal wells in Chunguang oilfield,a study on dynamic temperature profile water locating technique of thermal production with horizontal wells was carried out.Through entering the distributed temperature tester in the horizontal section and changing the production system,the temperature of water position is abnormal,and then the accurate water position can be located.Based on the understanding of water locating,the matching technique process was conducted.Temporary plugging protection of non-water point at the back end was carried out with liquid rubber stopper.After injection of low temperature gel and high strength nano plugging agent,the effluent section was gradually blocked,and a set of horizontal well water plugging technology for thermal recovery was formed.The application in the field has been conducted twice and achieved the goal of improving the high water cut condition of horizontal wells in thermal recovery,improving the production degree and development effect of horizontal section,and 226 tons of oil are added periodically.This technology provides a new technical method for the treatment of high water cut in horizontal wells.