The invention discloses an elastic positioning adjusting device for a conical pulley, which is applied to the technical field of automatic welding. The elastic positioning adjusting device is characterized by consisting of a conical pulley shaft, a conical pulley shaft sleeve, a double row angular contact bearing, a copper bush, a bearing cone cushion, an elastic retainer ring for shafts, a disc spring, a movable shaft, a shaft sleeve gland, an adjusting mounting base, a regulating hand wheel, an elastic retainer ring for holes, fastening screws and limit screws. The elastic positioning adjusting device has the advantage that: the elastic positioning adjusting device realizes that the conical pulley can reliably and stably rotate, has functions of accurate elastic positioning and wide-range position adjustment, has looseness-proof function, has compact and even structure, meets the design requirements for miniaturization and portability of a welding carriage and a track, and improves the positioning precision and walking reliability of the steel pipe automatic welding carriage.