Abstract: In this paper, time delay method is used to reconstruct the phase space of time series based on Takens phase space reconstruction theory. In the hyper dimensional phase space, we study the nonlinear characteristics of the time series. The similar sequence repeatability(rpt) of the phase space trajectory comparing itself is calculated and the RPT curves are plotted. The result proves that the ship radiated noise shows some geometric property between the stochastic Gause noise and deterministic Lorenz attractor. the RPT curves of same target show some similarity and different targets show some different characteristic as well. The method proposed ill this paper provides a new way for the non-linear analysis of the underwater acoustic targets.