The gas boilers of conventional flame always produce varying degrees of combustion products NOx and CO,which make the environmental pollution and energy waste.As a new way of combustion,catalytic combustion breaks the flammable limits of conventional flame combustion,and realizes the combustion of ultra-natural gas/air mixture under the flammable limits.Its combustion efficiency is higher,which can improve the ratio of energy utilization.The way of applying the catalytic combustion to gas boilers could solve the gas boilers' lower combustion efficiency,and achieve the purpose of energy-saving.On the basis of catalytic combustion burner Ⅰ,the catalytic combustion burner Ⅱ was designed according to the catalytic combustion and water heaters.The heat loss and thermal efficiency of catalytic combustion burner Ⅱwere analyzed and compared with that of flame combustion boilers.The results show that catalytic combustion burner Ⅱ's heat loss is not so high as considered,and its pollutant emissions are lower.