Abstract: Flue gas acid dew point is an important parameter in setting boilers´ exhaust temperature and preventing low-temperature corrosion.After considering the influencing factors of acid dew temperature（ADT） comprehensively， the volume fractions and partial pressures of SO3 and water vapor were considered to be the most direct influencing ones.After introducting empirical formulas for ADT， application conditions and calculation errors of modifier formulas for empirical formulas from the Soviet Union and other commonly-used empirical formulas were summarized. The pros and cons of each empirical formula were compared.The Soviet Union empirical formula that has considered the influence of ash is not suitable for low-sulfur fuels. The measurement of volume fractions and partial pressures of SO3 and H2SO4 in flue gas brings difficulties to other empirical formulas which have a wider application range，though. In conclusion， the prospect for ADT measurement and calculation is given based on the status quo and shortages of current researches.And considering different combustion conditions ，the empirical formulas with better accuracy， reproducibility and applicability are deduced .

Key words: boilers′ flue gas, waste heat utilization, low-temperature corrosion, acid dew point, empirical formulas, SO3, volume fraction, measurement device