Abstract: A feature extraction method of underwater echo, which takes advantage of the redundancy property of SWT (the Stationary Wavelet Transform) and the steady property of SVD (Singular Value Decomposition) was propostd. Since uses singular values of SWT coefficients matrix as feature vectors, it is a feature compress method with the K-L transform to multi-subspace signal obtained from SWT essentially. In contrast to the method of sub-band energy feature based on discrete orthogonal wavelet transform (DWT), this method acquires better results of lake trial data: (1) Under the same sample and distance within kinds, distance between kinds are larger than former; (2) correct recognition rates are also higher than the ones of the former, whether the training and testing samples are chosen from the same lake trail or not; (3) Sample sets varying, variety range of correct recognition rates is far less than the former. Thus this method can obtain more robust, effective features and better correct recognition results.