Abstract: Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing.One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimension.In this paper,local-geometric-projection method is applied to obtain low dimension element from various target radiated noise and the output phase portraits show obvious low dimension attractors.After that,attractor dimension and cross prediction error are used for classification.It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.