Polishing device capable of conveniently clamping workpiece and used for metal casting

The utility model discloses a metal casting polishing device capable of conveniently clamping a workpiece, which comprises a workbench, an auxiliary mechanism is arranged at the top of the workbench, the auxiliary mechanism comprises two connecting plates, the two connecting plates are both arranged at the top of the workbench, and the two connecting plates are arranged on the workbench. And a first threaded rod and a second threaded rod are connected to the interiors of the two connecting plates through bearings correspondingly, and the first threaded rod and the second threaded rod are fixedly connected through connecting ends. According to the metal casting grinding device capable of conveniently clamping the workpiece, through the design of the auxiliary mechanism, when a to-be-ground object needs to be fixedly ground, a first rotating plate is firstly rotated forwards, the first rotating plate rotates to drive a first threaded rod to rotate, the first threaded rod rotates to drive a second threaded rod t