The crystallization of the almino-silicate glass was investigated by optical transmittance measurement, X-ray diffraction and scanning electron microscope. The glass maintained its transparency after the heat treatment at 900℃, while it significantly devitrified at 1200℃. As reported in the previous works, the crystal phases were determined to be β-quartz and spodumene in 900℃ and 1200?? heat treatment respectively. All the measurements had been carried in FNCT, showing that the fundamental evaluation on the crystallization of glass can be made in FNCT.