This paper simulated SO2 concentration at three different CLP diameters based on the mathematic model of heat and mass transfer of Ca(OH)2 Liquid Particles (CLP)in Spray Drying Desulfurization Absorber(SDDA), the transient characteristics of water and solid weight in CLP, the temperature of CLP, the temperature of flue gas. The results show that while the CLP diameter, the temperature change rate of CLP and flue gas in crease, the mass increasing rate of CLP decrease. At the same time, the absorbing time to stable state of CLP becomes longer, the stable mass and the vaporizing rate of CLP increase. On the other hand, coupling simulation between the numerical and transient simulation process, the transient characteristics of absorbing SO2 for CLP are finished for CLP in SDDA at different flue gas temperature with CLP diameter 80 μm.With increasing the flue gas temperature, the mass increasing rate of CLP changes slowly, and the absorbing time to stable state of CLP also becomes longer. The SO2 absorbing efficiency increases, and its changing rate becomes fast.