Abstract: By calculation and analysis, it is shown that only energy balance alone can not wholly and actually response a reasonable degree of energy utilization, after considering not only the conservation of "quantity " but also the non-conservation of "quality", the way for increasing exergy efficiency of heat medium heater can be founded out. The key for increasing exergy efficiency of heat medium heater is to reduce the lost of exergy during combustion and heat transfer period. Take measures to increase adiabatic combustion temperature actually, such as reducing excessive air factor or preheating air, etc. An additional effective method is to rise the temperature of heat medium heater under acceptable process for heat medium heater.