The invention discloses a porous sound-absorption brick and a preparation method thereof. The porous sound-absorption brick comprises a sound-absorption layer and a sound-isolation layer compounded on the surface of the sound-absorption layer. The sound-absorption layer is composed of raw materials of, by weight, 60-85 parts of matrix, 10-30 parts of charcoal debris and 1-8 parts of saw dust. The sound-isolation layer is formed by raw materials of, by weight, 30-35 parts of charcoal debris, 50-65 parts of cement and 10-15 parts of saw dust. The porous sound-absorption brick has the advantages of being wide in sound-absorption frequency band and good in medium-high frequency sound-absorption performance and corrosion resistance.