The invention discloses a precision plane processing machine tool. The machine tool comprises a tool body, guide rails, a cutter, a spindle, a fixture, a rotating platform, a bottom support, a counterweight balance structure and a rotating platform axis inclination angle adjusting structure; the axis of the spindle, the axis of a linear feeding mechanism and the axis of the rotating platform are parallel with one another; the tool body adopts a square-box-shaped structure with five closed surfaces and is made of high-stability materials such as granite and the like; a sliding platform adopts the box-shaped structure with the polygonal section; the linear feeding mechanism comprises at least three linear guide rails, lead screws and a servo driving system, the geometric center of the axes of the guide rails is overlapped with the geometric center of the sliding table, and a stable statically-indeterminate linear guide structure capable of preventing the sliding platform from being inclined due to the eccentric force is formed; and three adjusting elements are symmetrically distributed around the rotating platform every 120 degrees. The machine tool can be widely applied to a precision plane grinding machine or milling machine and is few in axis number, high in precision, low in cost and adjustable in inclination angle.