Abstract: This paper presents a reliable method for recognizing chinese speech (putonghua) tones speaker independently. This method adopts an unbiased center-clipping autocorrelation algorithm to extract pitch periods. A two-dimensional decision vector for recognizing four chinese speech tones is obtained by passing the pitch period sequence through the procedures of data selection, error correction, data smoothing and curve fitting. The average correct rate of tone recognition for isolated Chinese syllables is over 98%.