The electrical resistance and structural changes on the crystallization process of sputter-deposited amorphous Ge100-xTex (x: 46-94) were investigated by two-point probe method. It was found that stoichiometric GeTe amorphous film crystallizes into rhombohedral GeTe single phase, which leads to a large electrical resistance drop, while off-stoichiometric Ge-Te amorphous films show two-stage crystallization or phase separation via single crystalline phase. Especially, Ge33Te 67 amorphous film crystallizes first into metastable GeTe2 single phase and then decomposes into α-GeTe and Te two-phase with a large electrical resistance change. The first crystallization temperature strongly depends on the composition. The Ge33Te67 film shows the highest crystallization temperature and activation energy for the first crystallization in the film with Te-rich composition.