Abstract: An extension tube for a vacuum cleaner comprises an outer tube, an inner tube slidingly sheathed in the outer tube, wherein the front end of the inner tube being embedded with a sealing component with an end extending out from the inner tube, the inner tube being provided with several rows of clamping grooves, and each row of clamping grooves being provided with a plurality of clamping grooves at intervals in the length direction, and a length adjustment component mounted on the rear end of the outer tube and used for selectively fixing the inner tube to adjust the length of the extension tube.