A staged expansion vertebra retaining device comprises a main body (10) and a screw (20) inserted into the main body (10). The distal end of the screw (20) is provided with a push block (21). One end of the main body (10) has at least two movable support units (14). Each movable support unit (14) is split by a U-shaped groove (13) to form at least two movable support surfaces (141, 142) which are spaced and arranged in the form of inner and outer layers. The movable support surface (141) is first expanded by the push block (21), and then the other movable support surface (142) is continuously expanded at an appropriate angle. Thus, the applied force of the graft operation can be dispersed effectively. The present invention is adjustable for the height of the vertebra, which can be adapted for most people. The present invention is labor-saving, precise, and quick for a graft operation.
