The utility model belongs to the field of biological experiment and chemical experiment tools, and particularly relates to a cleaning device capable of cleaning a conical flask fast. The cleaning device is mainly composed of a hand wheel, a rotating shaft, side rods, bottom rods, a spring and flannelette. The hand wheel is connected with the rotating shaft, the rotating shaft is connected with the two side rods through pins, each side rod is connected with the corresponding bottom rod through a pin, the two bottom rods are connected with the spring, and the side rods, the bottom rods and the spring are wrapped by a layer of flannelette. When the cleaning device is used, the side rods are pressed from the two sides to the center to be drawn close to each other, the bent spring is plugged into a neck of the conical flask, the hand wheel is pressed immediately to make the side rods and the bottom rods enter the conical flask completely, at the moment, the two side rods are automatically unfolded under the action of the spring, the hand wheel is rotated to clean the conical flask and is pulled up after cleaning is finished, the inner wall of the conical flask acts on the side rods to draw the side rods close to each other automatically so that the conical flask cleaning device can be taken out, and cleaning is finished. The conical flask cleaning device can fast clean the bottom and the side face of the conical flask at the same time and has the advantages of being good in cleaning effect, high in cleaning efficiency, simple in structure and low in manufacturing cost.