The limestone-gypsum flue gas desulfurization at the coal steam-electric plant applied widely, and take the currently widespread adoption of desulfurization, simple and wet method, spray fog dry method, electron beam method... etc., although electron beam method and limestone-gypsum desulfurization has a higher rate, it increase the unit price degree deeply, so the economy be not quite reasonable. Therefore, this text will take the fuzzy theories as the foundation, gather AHP analysis methods, carry on economy evaluation to the limestone-gypsum method, aims at providing a decision foundation for the power station's FGD. Thus, the evaluation result imply that the use of FAHP method to economy evaluation is reasonable and rationality.