Abstract: The compact heat transfer device is widely applied in the engineering technology,which contributed to the development of flow and heat transfer mechanism in a narrow channel.The development of flow and heat transfer mechanism and its related key issues are presented,including measurement methods and related issues on flow and temperature field,nucleate phenomenon and flow pattern,pressure drop,heat transfer characteristic and critical heat flux which is very concerned in the engineering.Aiming at the research actuality and issues on the flow and heat transfer mechanism in a narrow channel at present,the research directions on the flow and heat transfer mechanism in a narrow channel are suggested.