Abstract: The common methods characterizing chaotic system are briefly introduced in this paper.The most domestic and overseas advance in this filed are summarized,it is concluded that the main applications of chaos theory in hydroscience focused on hydrologic time series analysis and nonlinear prediction model.The most problems revealed in the past studies,such as delay time,data size,noise,are analyzed and discussed in this paper,so the hypothesis of chaotic character of hydroscience problems is reasonable.But as for any finite and noisy time series,it is almost impossible to determine strictly whether the phase-space is a determinate or stochastic system because whether pure stochastic or chaos is an ideal state of mathematics. Any observation achieved through single method may not be used as evidence of chaos in hydroscience problems,can only be regarded as chaotic character.Various ways should be employed to characterize chaos of hydroscience and define whichone, chaos or stochastic is dominating.Finally,we suggest that the fractal chaos dynamical system and the mean of combining chaos with neural net provide several new methods in the future studying.