Abstract: A telescopic adapter device for a dredging machine includes a protective cover at an exit of a flexible shaft of a dredging machine, a connector detachably connected to the protective cover, a flexible shaft conduit with an inner end fixed in an inner hole of the connector, and a sliding conduit sleeved on an outer wall of the flexible shaft conduit, where the sliding conduit includes an inner end provided with a clamping joint for clamping the flexible shaft conduit, and an outer end provided with a bending portion; and a rubber jacket is sleeved on an outer wall of the bending portion. The telescopic adapter device for a dredging machine not only can prevent damage to a glazed surface at a corner of a toilet, but also improves a turning capacity of the flexible shaft.