Workpiece clamping device

The utility model relates to a workpiece clamping device which comprises a fixed seat, an extrusion piece arranged in the fixed seat in a sliding mode and at least two expansion pieces arranged on the extrusion piece in a surrounding mode. The fixed seat is provided with a hollow cylindrical opening; the extrusion piece is a cone or a circular truncated cone, the extrusion piece is coaxial with the cylindrical opening, one end, with a smaller radius, of the extrusion piece is a small-diameter end, and the small-diameter end extends out of the outer side of the opening; each expansion part is provided with an inner curved surface and an outer curved surface, and the inner curved surfaces of the expansion parts are attached and contacted with the outer curved surfaces of the extrusion parts, so that the outer curved surfaces of the expansion parts enclose to form a cylinder; gaps are formed among the expansion pieces; the first end of each expansion piece is clamped on the inner side of the opening, and the sec