Abstract: Wear map research is one of the hot points in tribology. It has been applied to many materials for classifying and ordering of wear data and for revealing of the relationship between the competing wear mechanisms. However, little attention has been paid to the relationship between the transformation of wear mechanisms and the growth of crack in subsurface concerning the research on wear map up to now. Thus the tribological properties of aluminum alloy sliding against AISI 1045 steel were examined, with an emphasis on the transformation of the wear mechanisms under different testing conditions and on the relationship between the wear mechanism transformation and the generation of micro cracks in the sub worn surface. Accordingly, the wear map of 2024 aluminum alloy under dry sliding against the mild steel was constructed based on careful analysis of the worn surface, cross section, transfer film and wear debris by means of scanning electron microscopy and energy dispersive spectrometry. As the results, 2024 Al alloy was characterized by abrasive wear and delamination wear at very small normal load and slow sliding speed. It was characterized by severe melt wear and adhesion transfer onto the counterface at very high normal load and sliding speed. The transformation of the wear mechanisms is highly dependent on the direction of the growth of cracks in sub worn surface.