Abstract: Nonlinear dynamic method is used in studying the Chinese spoken in normal speed,the improved correlationdimension algorithm is made for the characterization of speech signal,the reconstructed phase space and correlationdimension curves of fricatives and vowels are also given.It is found that because of the different mechanism betweenthem,the correlation dimension algorithm can distinguish fricative from vowel.Also our study shows that it can provideinformation for distinguishing four basic tones in mandarin speech.