Abstract: In the reverberation room, the sound absorption performances of the open-cell aluminum foam of different thicknesses under different back-cavity depths are tested, and the sound absorption coefficients in different conditions are obtained. The results shows that when the frequency is lower than 630 Hz, the sound absorption coefficients of the foam aluminum panel with different thicknesses gradually increases with the increase of the back-cavity depth. In the frequency range of 630-5 000 Hz, when the thickness of foam aluminum material is greater than 4 mm and the depth of back-cavity is greater than 40 mm, the sound absorption coefficients of the foam aluminum panel with different thicknesses are greater than 0.6. The noise reduction coefficients of the open-cell aluminum foam with different thicknesses under different back-cavity conditions are calculated, which provides parameter selection for the practical engineering application of aluminum foam.