A telescopic tube assembly includes an outer tube and an inner tube which is telescopically inserted in the outer tube. A first stabilizing unit and a second stabilizing unit respectively located in a gap between the inner and outer tubes to make the inner tube stably moved relative to the outer tube. The first stabilizing unit includes two plates. The outer surface of each of the two plates is in contact with the inner surface of the outer tube, and the inner surface of each of the two plates is in contact with the outer surface of the inner tube. The inner tube is assembled to the outer tube by the first and second stabilizing units.