Abstract: A detection method of radar small target in a strong clutter environment is proposed. On the basis of singular value decomposition theory, the first order and second order difference spectrum of singular values is used to select the singular values in various combination. Radar echo signal is decomposed into different compositions by inverse singular value transformation, thus realizing the clutter suppression and small target highlights. The experiment shows that the method can effectively suppress the strong clutter and improve the signal to noise ratio 7dB of small targets.