Abstract: A new inverse method, matched-filter approach, has been applied to estimate the sound impedance of underwater sediments. The theory and algorithm of this approach are discussed in the paper, and an improved method is presented so that the attenuation effect can be considered in this approach. Through the inverse results of simulated soars signals, it has been shown that the matched-filter approach is a simple and effective inverse method, which way be a useful tool to derive the impedance model of underwater sediments.