A reshaping device for reshaping a workpiece, includes a worktable, a reshaping assembly, a measuring unit, a positioning assembly, and a controller electrically connected to the reshaping assembly, the measuring unit, and the positioning assembly. The positioning assembly includes a pair of positioning subassemblies and a movable supporting subassembly. Each positioning subassembly comprises a supporting bracket and two positioning members, the two supporting brackets are distributed on the worktable, spaced from each other, for holding the workpiece. The movable supporting subassembly comprises two transmission members and two driving members. The two transmission members are laminated together and disposed on the worktable. The two driving members are respectively assembled to the two transmission members and drive the two transmission members to slide along different directions, thereby supporting the workpiece. The present disclosure further discloses a positioning assembly.