Deep and long hole roller milling key groove machining tool

The utility model belongs to the technical field of machining tools, and particularly discloses a deep and long hole roller milling key groove machining tool which comprises a lathe body, a tool bit assembly and a positioning assembly, the tool bit assembly comprises an installation base, a milling head motor and a milling cutter, the installation base is installed on a tool bit connecting rod, and the center axis of the installation base coincides with the center axis of the tool bit connecting rod; the positioning assembly comprises a plurality of positioning structures which are evenly distributed in the circumferential direction of the mounting base. Each group of positioning structures comprises at least one group of positioning parts, each group of positioning parts comprises rollers and rotating shafts, mounting frames in one-to-one correspondence with the positioning parts are arranged on the mounting seat, the rotating shafts are fixed on the mounting frames, and the rollers are rotationally connecte