A new toolwear monitoring method is presented by using the linear pre d ictive cepstrum coefficient (LPCC). Firstly, audible milling sound is characteri zed by LPCC. In order to discover the law between LPCC and tool wear, statistics are collected including calculation of the F ratio of LPCC components, analysis of the relationship between the relative components of LPCC and cutting time. T he results indicate that the weighted sum of the relative LPCC components extrac ted from audible milling sound can effectively reflect the tool wear.