Abstract: Taking the tests of certain additive in desulfurization systems of different capacity for example,analyze the evaluation methods and experimental results of desulfurization additive applicating in engineering.The results show that the desulfurization additive can improve desulfurization rate of capacity system.The application effects and evaluation indexs of desulfurization additive are decided by working condition,working condition matching,data statistics and calibration,systematicness and economical efficiency of system.