Variable-diameter flange positioning tool

The invention discloses a variable-diameter flange positioning tool, and relates to the field of machining, the variable-diameter flange positioning tool comprises a base, a left rack, a right rack, a left rotating disc, a right rotating disc, a clamping assembly, a rotating device, a correcting device and a detecting assembly, the left rotating disc is rotatably connected with the left rack, and the right rotating disc is rotatably connected with the right rack; clamping assemblies are arranged on the left rack and the right rack correspondingly, and a correcting device is arranged on the right rotating disc. By arranging the clamping assembly, the circle centers of the two flanges can be automatically aligned after the two flanges are positioned, the correcting device can automatically correct the conical pipe, so that the conical pipe and the two flanges are concentric, the conical pipe, the two flanges and the two flanges are synchronously pressed and assembled, repeated positioning and clamping are not n