The invention relates to a bicycle expansion brake hub assembly, which comprises a hub and a centre shaft, wherein the hub is composed of a rim and a disk chuck, and one end of the hub is provided with a brake component. The brake component is composed of an expansion block, a roller skeleton, an inner baffle plate, an outer cover plate, return springs, a torsion spring and brake tiles, and the brake tiles are uniformly distributed around the inner wall of the shell of the disk chuck. A notch slot is arranged in the roller skeleton, and rollers are arranged in the notch slot. The inner baffle plate and the outer cover plate are respectively sheathed on flat heads of two sides of a plummer block. The expansion block is hexagonal and is embedded in the inner cavity of the roller skeleton, and the outer side of the expansion block is fixedly connected with an end plate. A brake wrench is arranged on the end plate, and the outer cover plate is arranged at the outer side of the expansion block. The torsion spring is arranged between the end plate and the outer cover plate on the outer side of the expansion block, and each return spring is hooped in an arc-shaped groove of the excircle of each brake tile. The bicycle expansion brake hub assembly has the advantages of compact structure, firm and reliable whole, compression and vibration resistance, large bearing capacity and good brake performance, is not easily damaged, is durable in use, and can be used as a front hub or a rear hub.