The invention discloses a bent arm milling fixture. The bent arm milling fixture comprises a fixture base, a positioning seat, a vertical positioning mechanism and a horizontal positioning mechanism; the fixture base is a rectangular block; the positioning seat comprises a horizontal fixing face and a vertical fixing face, the horizontal fixing face is fixed to the fixture base, one side of the vertical fixing face horizontally extends to be provided with a vertical positioning plate, and the vertical positioning plate is provided with a vertical positioning hole; the vertical positioning mechanism comprises a supporting rod which is installed in the vertical positioning hole, and the top end of the supporting rod stretches upwards out of the vertical positioning plate; the horizontal positioning mechanism comprises a horizontal supporting rod and a pressing threaded rod which are fixed to the other side of the vertical fixing face, the pressing threaded rod is located below the horizontal supporting rod, the end of the horizontal supporting rod is connected with an L-shaped supporting plate, the end of the pressing threaded rod is connected with a pressing plate, and a U-shaped groove with an upward opening is formed by the pressing plate and the L-shaped supporting plate in a surrounding mode. According to the bent arm milling fixture, bent arm fixing is reliable, and positioning is accurate.