Abstract: A new type of foamed composite sound absorbing materials mainly made from PVC resin, EPR and rockwool was investigated. The benefits offered by such products include high stiffness, good water resistance, flame retardancy, lower material costs per unit volume, and especially good acoustic performance at both medium and low frequencies. The effects of unit weight, thickness and surface treatment on acoustic property were discussed in this paper. The results showed that each of them had great effect on the acoustic property. Compared with foamed PVC materials, the materials have much better acoustic performance.