High-resolution photoluminescence (PL) measurement was carried out for copper aluminum disulfide (CuAlS2) powder at 12 K. Several sharp PL lines were observed in the range from 3.580 to 3.320 eV. The emission peaks at photon energies from 3.566 to 3.459 eV were attributed to free-exciton (FE) and bound-excitons (BE). The several weak emissions at below 3.476 eV were clarified to be phonon replicas (PR) by Raman scattering and in the viewpoint of exciton-phonon interaction. We observed the one, two and three-phonon replicas related to E(LO, TO) and B2(LO, TO) vibrational modes in chalcopyrite structure. It was suggested that the strong interaction between excitons and optical phonons took place in obtained CuAlS2 powder.