Three-in-one fixture for shape processing of rocker arm and use method of fixture

The invention discloses a three-in-one fixture for shape processing of a rocker arm and a use method of the fixture. The three-in-one fixture is structurally characterized in that a slideway is arranged on a rectangular base, bolts are vertically arranged on the base, bottom parts of the bolts are arranged in the slideway and can move in the slideway, pressure plates are arranged at the upper parts of the bolts, and nuts matched with the bolts for use are arranged on the pressure plates; a rhombus pin, a cylinder head adjusting support body I, a straight pin and a cylinder head adjusting support body II are arranged on the base to form a horizontal line, and the arranging direction of the components are parallel to the direction of the slideway, and the position of the horizontal line is below the pressure plates. With adoption of the structure and the method, the three-in-one fixture for shape processing of the rocker arm and the use method of the fixture have the advantages of simple structure, convenience in operation, high working efficiency and small processing error, and solve the technical problems of low production efficiency due to requirement for three kinds of assembling tools and high probability of out-of-tolerance during three times of clamping for part processing in the prior art.