A method for forming a Ge-on-insulator structure is provided, comprising steps of: forming a Ge layer (1200) on a substrate (2000); treating a first surface of the Ge layer (1200) to form a first semiconducting metal-germanide passivation layer (1300); bonding the first semiconducting metal-germanide passivation layer (1300) with a silicon substrate (1100), wherein on a surface of the silicon substrate (1100) an oxide insulating layer is formed; and removing the substrate (2000). Further, a Ge-on-insulator structure formed by the method is also provided.