The invention discloses an expandable suitcase, and belongs to the field of bags and suitcases. The suitcase comprises a main case, a draw bar and moving wheels, a rotating shaft is inserted into an inner cavity of the fixed seat; one end of the rotating shaft is connected with a rotating handle; two first gears are fixedly arranged on the rotating shaft in a sleeving manner; the first gear is engaged with a second gear, the left end of the second gear is fixedly connected with a screw rod, a fixed block is in threaded connection with the screw rod, the top end of the fixed block is fixedly connected with a sliding plate, the sliding plate penetrates through a through hole in the left end of the fixed seat and is fixedly connected with a sliding seat, and the sliding seat is connected withan expansion box through a connecting plate. By arranging the rotating shaft, the first gear, the second gear, the rotating handle, the screw rod and the sliding block, the sliding plate can move leftwards, and the sliding plate can drive the expansion box to slide leftwards through the sliding seat, so that the volume of the luggage is increased, more articles can be carried, and convenience isbrought to travel.