A driving structure for a wheel hub of a bicycle includes a wheel hub having a ratchet wheel, a ratchet base having an operating member and connected to the wheel hub, an engaging block and an elastic member both assembled onto the operating member, the elastic member abutting against the engaging block so that the engaging block is engaged with the ratchet wheel, a rotating ring assembled between the ratchet wheel and the operating member and having a plurality of abutting plates, each abutting plate abutting against the corresponding engaging block, an elastomer defined on the operating member and abutting against the rotating ring. Under this arrangement, the ratchet wheel simultaneously engages with the engaging blocks, because of the rotating ring and the elastomer.