Combined hydraulic fastening device

The utility model relates to a combined hydraulic fastening device. The combined hydraulic fastening device comprises a piston, a cylinder body, a supporting sleeve and a stretching screw sleeve, wherein the outer diameter of the piston is provided with a stepped wall surface; the inner diameter of the piston adopts a threaded structure; an oil filling hole channel is arranged at the upper end of the piston along the axial direction; the cylinder body is coaxially sleeved outside the piston; the inner wall of the cylinder body is provided with a stepped wall surface which is in tight fit with the piston; an oil filling hole is formed on the side of the cylinder body; the supporting sleeve is sleeved at the outer boss end of the cylinder body; and the stretching screw sleeve is fixed in the piston through thread and positioning screws. The combined hydraulic fastening device can stretch and fasten various bolts with different diameters; the hydraulic fastening device does not need the stretching screw sleeve w