The invention discloses a roll forming method of a titanium alloy high cylindrical ring forging, wherein the high cylindrical ring forging is roll-formed and has a thin wall and excellent structure and performance. The technical scheme is as follows: feeding a pre-heated follow-up mould sleeve and a titanium alloy pre-rolled blank sleeve which is heated to a deforming temperature into a ring rolling mill; positioning the two workpieces by utilizing a main roller, a core roller, holding rollers and upper and lower conical rollers of the ring rolling mill; and starting the ring rolling mill, wherein the core roller of the ring rolling mill performs radial feed motion toward the main roller and rolls the pre-rolled blank in the follow-up mould sleeve together with the main roller with a rolling force of 200-4,000 KN so that the pre-rolled blank is widened radially at a speed of 5-10 mm/s and the wall thickness is gradually reduced; after the deformation of the pre-rolled blank reaches 25-45%, the pre-rolled blank is rolled into a high cylindrical ring forging; and during the rolling, the upper and lower conical rollers and the two holding rollers are not radially widened to move outwards with the pre-rolled blank. The minimum of the wall thickness of the titanium alloy high cylindrical ring forging roll-formed by the method is 25 mm, and the maximum of the height-thickness ratio is 25 mm; and the forging is mainly applied to rotational parts such as a cylindrical shell and the like used in the fields of aerospace and the like.