Abstract: The effect of different fillers such as hollow glass microsphere, pulverous coal ash and foam polymer on water insertion loss of sound isolation rubber material were studied. The results showed that the water insertion loss of the rubbers filled with such fillers were greatly improved. The effect of the hollow glass microsphere was the first evident, the pulverous coal ash the second and the equal mixture of three kinds of above mentioned fillers was the last. 30 parts by weight of hollow glass microsphere for hundred parts rubber matrix by weight was the best usage.