The invention provides a milling machine jig for machining studs of a floating wall tile of an annular flame tube and a locating method. The milling machine jig comprises a linear sliding plate, wherein the linear sliding plate is installed on a jig base through slideways. A rotating base is arranged on the linear sliding plate and comprises a rotation curved surface, wherein the rotation curved surface and the center line of the annular flame tube are concentric. A rotating sliding block which can slide is arranged on the rotation curved surface of the rotating base. An X-direction V-shaped block and a Y-direction V-shaped block are arranged above the rotating sliding block, are perpendicular to each other, and are connected with V-shaped block support columns through hinge pairs respectively, hinge holes are strip-shaped holes, and the V-shaped block support columns are fixedly arranged on the jig base. The locating method comprises the steps that the tile with the studs is installed on the rotating sliding block, X-direction locating is conducted on the studs through the Y-direction V-shaped block, Y-direction locating is conducted on the studs through the X-direction V-shaped block, and the position of the rotating sliding block and the position of the linear sliding plate are locked. According to the milling machine jig and the locating method, accurate locating and quick locating can be conducted on the studs, arranged in different spatial directions, of the tile, and therefore numerical control machining of the studs of the tile is achieved, and the production efficiency is improved.