The invention belongs to the field of biology experiment and chemical experiment appliances, and specifically relates to a conical flask cleaning device whose brush can be rapidly changed. The cleaning device is mainly formed by a hand wheel, a rotating shaft, a side rod, a bottom rod, a quick-changing joint, and a locknut. The rotating shaft and the quick-changing joint are cooperated with a groove-type bulge through a groove. The quick-changing joint is connected with the threads of the locknut, to compress the rotating shaft with the quick-changing joint. The cleaning device realizes quick changing of a brush, to adapt to cleaning of conical flasks in different models. Three clamping jaws are uniformly distributed in a circumferential direction and are on the outer side of a shaft sleeve. When the device is used, an automatic centering action of the three jaws can limit the rotating shaft of the cleaning device on the central axis of the conical flask, so cleaning load-carrying is uniform. The conical flask cleaning device can rapidly clean the bottom and the side surface of the conical flask, and is characterized by good cleaning effect and high efficiency, and the brush can be changed rapidly. The device is common in use, and saves resources.