The experiments were conducted to focus on the desulfurization and evaporation characteristics of lime slurry droplets at 298 K to 383 K. We designed an evaporation-reaction chamber with quartz glass windows. The monodisperse slurry droplet stream was injected into the evaporation reaction chamber, and the inlet gas components (air, air+SO 2 ) were introduced into the reactor. We applied the magnified digital in-line holography to measure the droplet parameters and calculated the evaporation rate. The effects of temperature, droplet concentration, and the effects of SO 2 concentration of the evaporation rate on Ca(OH) 2 droplets were discussed. Moreover, the Ca(OH) 2 droplets under different experimental conditions were sampled, and the droplets were observed and analyzed using an off-line microscope. The evaporation rate of the Ca(OH) 2 droplet increased at first, and then decreased during the falling process, and remained constant at last. The average evaporation rate of the Ca(OH) 2 droplets increased significantly with the temperature increasing.