The invention discloses an FSAE racing car rear wheel hub capable of realizing quick disassembling and assembling of an axle shaft and a disassembling and assembling method. The rear wheel hub comprises a three-column-groove shell and a sealing device. A through cavity is formed in the center of the three-column groove shell. The through cavity is sealed by the sealing device. The sealing device comprises an end cover, an end cover gasket, a sealing circular ring and a sealing circular ring gasket. The end cover and the sealing circular ring are correspondingly matched with the through cavity.The sealing circular ring is pressed on the through cavity by the end cover. An annular stepped table is arranged on the center of one end of the sealing circular ring, and the end cover gasket is pressed on the annular stepped table by the end cover. A circular groove which is concentric with the sealing circular ring is formed in an outer cylinder surface of the sealing circular ring, the sealing circular ring gasket is arranged in the circular groove, and the outer surface of the sealing circular ring gasket is in tight contact with the inner surface of a rear wheel hub body after assembling. When the axle shaft is disassembled, one end of the axle shaft impacts the sealing circular ring to enable the sealing circular ring and the axle shaft to move towards the outer side of a vehicleuntil the other end of the axle shaft falls from a differential mechanism groove shell to achieve the disassembling of the axle shaft. The rear wheel hub simplifies the disassembling and assembling process of the axle shaft and shortens the maintenance time.