The crystallization mechanism of {{{{ { { {Bi }_{4 }Ｇe }_{3 }O }_{12 } }}({{{{ { {Bi }_{2 }O }_{3) } }}:{{{{ { Ｇe O}_{2 } }}=2:3 glass has been studied by using the non-isoth-ermal modified Ozawa equation. XRD and DTA have been used for the measurement of structural and thermal change during the transition with the sample prepared by the twin roller melt quenching method. It is found there exists middle stage {{{{ { { {Bi }_{4 }Ｇe }_{3 }O }_{12 } }}({{{{ { {Bi }_{2 }O }_{3) } }}:{{{{ { Ｇe O}_{2 } }}=1:1) crystalline phase. The obtained activation en-ergy and Avrami parameter for BGO(1:1) crystalline phase. The obtained activation en-ergy and Averami parameter for BGO(1:1) transition are 4.47$pm$0.04 eV and near 1.5 respectively. These in-dicate the crystallization occurs through the 3 dimensional diffusion controlled growth