Abstract: In order to investigate a nitric acid modification- activation process affected to the flue gas desulfurization performances of the pyrolytic coke,with the lignite pyrolytic coke as the raw material,the evaluation of desulfurization performances was conducted after the nitric acid modification and steam activation and a study was con ducted on different activation conditions affected to the desulfurization performances of pyrolytic coke. The results showed that when the solid- liquid ratio was 2.5 : 1. 0, a burning temperature was 800。C ,burning time was 4 h and nitric acid solution volume fraction was 25%, after the modification of the nitric acid,the SO2 conversion rate of the modified pyrolytic coke would keep a time over 70% increased with 6 min. Based on the circumstances, a steam activation would be conducted on the pyrolytic coke wh en the nitric acid modified. The results showed that the activation temperature would be the most obvious factor affected to the desulfurization activity and the temperature of 800 °C,the steam flow of 0.264 LI h and the activated time of 1. 5 h would be the best activation of the modification- activated pyrolytic coke. Under the condition,SO2 C onversion rate would keep over 70%time increased with 2 min in comparison with the non- activation time.