The large size, high quality terbium gallium garnet ((Tb3Ga5O12, TGG) crystal is urgently needed for the high power, all solid state laser at present. The TGG single crystal along the (111) direction was grown by Czochralski method. The spiral morphology phenomenon was observed, which can influence the quality and utilization ratio of the crystal. Through analyzing the characteristic of volatile matter and liquid melt, the mechanism of spiral morphology is interpreted and the solution is put forward. We have successfully grown completed TGG crystal with size of 44 mm×70 mm. By comparing the transmittance between cylindrical and spiral TGG crystals, the reason of spiral growth is further explained.