Abstract: Desulfurized gypsum is the solid waste from wet flue gas desulfurization technology of power plants.It can not only waste valuable resources，but also pollute the environment.In order to promote the added-value of utilization，hemihydrate gypsum whiskers were prepared by salt solution method and using desulfurized gypsum as materials.The influences of the concentration of sodium chloride，reaction temperature，ratio of liquid to solid，and pH on conversion rate and the effect of the content of citric acid on morphology were investigated.The hemihydrate gypsum whiskers were characterized by scanning electron microscopy，X-ray diffraction and infrared spectroscopy instruments.The mechanism of the effect of citric acid on the morphology was also studied.The results showed that the best technological conditions were as follows:mass fraction of sodium chloride was 20%，reaction temperature was 100 ℃，reaction time was 2 h，ratio of liquid to solid was 5∶1，and mass fraction of citric acid was 0.25%.Under the optimal conditions，the length of hemihydrate gypsum whiskers was 50～100 μm and the slenderness ratio was （30～50）∶1.

Key words: desulfurized gypsum, hemihydrate gypsum whiskers, salt solution method, conversion rate