The utility model discloses a height-adjustable trundle for a sweeper. The road sweeper comprises a guide wheel support welding part, front support welding parts are arranged on the two sides of the guide wheel support welding part, the guide wheel support welding part is connected with a sweeping brush cover bent pipe through the front support welding parts, and a sweeping brush protective coveris installed on the side, away from the guide wheel support welding part, of the sweeping brush cover bent pipe. A guide wheel adjusting pad and a guide wheel shaft bushing are arranged on a trundle bracket from bottom to top; wherein the guide wheel shaft bushing is in clearance fit with the shaft part of the guide wheel; the guide wheel bushings are in clearance fit with the welded circular tubes of the front bracket; therefore, the guide wheel can freely rotate on the front support seaming, the upper end of the guide wheel support seaming is positioned with the front support seaming throughone guide wheel shaft bushing at the top of the guide wheel support seaming, and the other guide wheel shaft bushing at the top end of the guide wheel support seaming is limited in the height direction.