The invention discloses a fixture for clamping steam inlet and outlet sides of intermediates of blade roots during milling, and relates to a fixture. The fixture comprises a bottom plate, an oblique pressure plate mechanism, a flat pressure plate, a first double-end stud, a guide slider, a positioning slider and a barrier. The bottom plate is horizontally arranged, the lower end of the first double-end stud is inserted in the upper surface of the bottom plate, the upper end of the first double-end stud is connected with the flat pressure plate, the lower surface of the flat pressure plate is parallel to the upper surface of the bottom plate, the guide slider is arranged on the upper surface of the bottom plate and is positioned below the flat pressure plate, the positioning slider and the barrier are mounted on the upper surface of the guide slider side by side via a plurality of bolts, and the oblique pressure plate mechanism is arranged on the upper surface of the bottom plate. The fixture has the advantages that problems of large quantities of fixtures, waste of labor and troublesome management and operation when intermediates of blade roots of blades of steam turbines are clamped during milling can be solved; the fixture is used for blade machining.