Abstract: The dry cutting experiment of tin bronze alloy at high speed with PCD tools is carried out. The tool wear morphology was observed by the Scanning Electron Microscopy (SEM) and the chemical composition of wear area was detected with the aid of X- ray Energy Dispersive Spectrometer (EDS), and the mechanisms of tool wear were studied. The results show that the wear morphology of PCD tools is characterized by the flaking on the rake face and the slight breakage on the flank surface. At the same time, it is also accompanied by brittle failure under the impact of mechanical stress and thermal stress, resulting the breakage of the cutting edge, overall fracture of cutting edge and large-scale flaking of the rake and flank face. The oxidation wear and diffusion wear under high temperatures are the main reasons of tool wear.