Abstract: The influence of various factors on fretting wear behaviour of metals and alloyshas been widely investigated,but few papers are available on the relationship between composition of wear debris,compacted oxide layer formation and the hardness of specimen. The relationship between composition of wear debris,fretted surface morphology,compacted oxidelayer formation and the hardness of carbon steel has been studied,and the morphological cha-racteristics of the fretted surface and the formation of compacted oxide layer are discussed inrelating to the fretting wear behaviour observed.Three series of pairs with different hardnesscombination were tested using the contact configuration of a cylinder specimen and a flat platespecimen on the SRV fretting tester. The results reveal that the fretting wear resistance ofcarbon steel may be greatly increased by enhancing its hardness,However,when upper softercylindrical specimen with different hardness were fretted against lower flat specimen,the hard-ness has little influence on fretting wear of carbon steel.The fretting wear debris consists ofFe2O3 and Fe. The iron content in wear debris is controlled by hardness of the specimen,thehigher hardness,the lower iron content in wear debris and smaller wear volume of the specimen. For the specimen with lower hardness in this test,fretting wear behaviour is mainly governed by the removal rate of oxide particles which depends on the morphological characteristics ofafretted surface.