The invention relates to a fixture, in particular to a full automatic hydraulic fixture device used for a milling machine or a boring machine, which comprises at least two fixture bodies for clampingparts on a working table, a clamping mechanism arranged above a base through a support, and a guide rail fixed on a working table top. The base of each fixture body is arranged on the guide rail; anda moving mechanism for moving the base along the guide rail and a hydraulic locking mechanism for fixing the base on the guide rail are arranged on the base. The full automatic hydraulic fixture device has the advantages of wide clamping range, high mounting and positioning precision, and high automation degree, thereby greatly reducing labor intensity of operators and improving production efficiency, is particularly suitable for high strength cutting of shaft parts, and is widely applied to the manufacturing fields of various processing such as the milling of a flat head, the milling of a circular arc at the root part of the flat head, the milling of a key slot, the processing of a wabbler of a supporting roll, the beveling of a flat surface and the wabbler, the drilling and the rigid tapping processing to complete the processing of shaft parts with different diameters and different lengths through a milling machine or a boring machine.