Using fly ash from the power plant and SiO2 as the main raw materials, glass-ceramic was prepared by melting method. By means of DSC, XRD and SEM, the crystallizations of CaO-Al2O3-SiO2 system glass-ceramic were studied. The results show that it is more and more difficult to crystallize as the content of SiO2 increases. When the content of SiO2 reaches to 41.5%, the crystal nucleus form in the form of shuttle shape, the crystals develop in the same direction for a certain zone. But the crystals develop into hexagon shape finally when they are heated for 1 h at 1100°Cafter nucleation at 780°C.The developed crystals are anorthite. The sizes of crystals are between 1- 1.5μm, their microhardness can reach HV804.