Choosing lignite mixing with sawdust as object, the effect of calcium salt catalysis on SO2 and NOx emission was analyzed by using circulating fluidized bed reactor. The ash elements groups and mineral composition of ash samples were measured through X-ray fluorescence spectrometer(XRF), X-ray diffraction(XRD) and inductively coupled plasma atomic emission spectrometer(ICP). The result showed CaCO3 had a certain effect on SO2 and NOx emission reduction. The addition of limestone had obvious effect on NOx emission reduction with α=1.0. NOx production reduced with the decreasing of sawdust content. The removal of SO2was controlled by reaction temperature. Under the condition of temperature of 700~900℃ and Ca/S of 2.0, desulfurization was the best. The ash melting phenomenon disappeared with the effect of CaCO3. 