Crystallization behavior of the fresnoite-type Ba2TiGe2O8 (BTG) with a large optical nonlinearity has been examined in the BaO-TiO2-GeO2 glass thin film fabricated by a RF sputtering technique and the corresponding glass (same composition of thin film, i.e., 28BaO-22TiO2-50GeO2). Both the glass thin film and the corresponding glass were crystallized by the heat-treatment, keeping a good transparency. Initial formation of BTG phase followed by the BaGe4O9 phase was confirmed in the both glass samples. In addition, the BTG crystallites in the both glass samples indicated the preferential (211) orientation. Crystallization behavior confirmed in this study was quite different from the previous study about the 30BaO-15TiO2-55GeO2 glass.