This paper researches the surface temperature measuring methodfor special vertical-plate heat-transfer element together with the special vertical-plate down film evaporator. From all measuring temperature system, thechoice of measuring temperature element, and the methods of the thermocoupleweld and its arrangement are introduced. The new method for symmetric thermocouple arrangement is given when the averaging temperature of the specialvertical plate with non-equal temperature field. It can accurately measure thesurface temperature and is very important for heat-transfer theory about thevertical-plate down film evaporator to research.