Evaluation of the afterburning energy of aluminized explosives is challenging. An experimental method based on a simple sleeve-slider apparatus and detonation test is proposed in the present work by which the afterburning energy and its releasing rate can be calculated indirectly. When a little charge of aluminized explosive is detonated in a sleeve, the slider will be propelled rapidly by the detonation products inside the sleeve. Only the displacement history of the slider needs to be recorded by high speed photography, and the pressure and the specific volume of the aluminized explosive detonation products with time can be derived. Assuming the slider is rigid enough and the pressure is uniform in the sleeve, the afterburning energy can be evaluated practically. Before actual experiments are conducted, numerical simulations are used to validate the assumptions of the method; then, the experimental apparatus is designed, and several detonation tests are conducted. For comparison purposes, pure TNT and aluminized explosives are used in the experiments, and the results reveal that pure TNT does not release afterburning energy, which is expected, while aluminized explosive products release a large amount of afterburning energy, which makes the pressure decay more slowly. The afterburning energy rate is also obtained.