The utility model discloses a boring special fixture of caliper piston, its characteristics are: including anchor clamps body and clamp bolt, be provided with on the anchor clamps body the circular recess that can hold caliper piston and with the constant head tank of circular groove connection's the shape of falling the halfpace, be provided with the through -hole on the lateral wall of the corresponding circle connected in star of anchor clamps body, be provided with the spout that corresponds with the through -hole on the cell wall of circular recess, be provided with movable clamping block in the spout, the last screw that corresponds with the through -hole that is provided with of movable clamping block, the clamp bolt pass the through -hole and with movable clamping block 's screw spiro union, still be provided with location drilling on the anchor clamps body. The utility model has the advantages of simple structure, caliper piston can install in circular recess to with the tight caliper piston in movable clamping block top to the cell wall of constant head tank on, can aim at the location operation of driling, can also continue after the drilling to move it and directly carry out the burring operation to the burring work area, need not to change anchor clamps, its operation is very simple, is favorable to improving work efficiency.