Abstract: In order to introduce fractal geometry to the tribology research, the wear mechanism of polyetheretherketone (PEEK) was investigated under the unlubricated conditions, morphology of debris from PEEK were also studied. The experimental results revealed that the wear debris exhibited distinct morphologies corresponding to the various wear rate with the increment of loading. Fractal geometry was found to be able to quantitatively describe the wear debris state. The relationship between loading and fractal dimension of wear debris reflected changes in wear of PEEK. On the basis of this research, an in situ wear monitoring technique for the frictional components made from polymers can be developed.