Electron Back Scattered Diffraction(EBSD) analysis was carried out to investigate boundary characteristics of Abnormally Grain Grown(AGG) Alumina. To obtain whole orientation information from AGG Alumina, separately measured EBSD mapping data was combined together to be satisfied with condition of minimum misorientation, which is called Montage technique. The orientation information from 0.5 x 3.5 mm and 0.35 x 1.00 mm sizes of AGG alumina was obtained. Misorientation distribution in Normally Grain Grown(NGG) Alumina was very close to the random misorientation boundary. Misorientation distribution between AGG and NGG alumina showed random boundary characteristics in 0.5 x 3.5 mm AGG alumina. Large part of captured grain inside AGG grain has high angle boundary of 90degrees.