The impact-abrasive wear model was investigated in bainitic steels using an impact-abrasive wear testing machine. The results showed that a high H/KIC (hardness-to-fracture toughness) ratio could improve wear resistance, but the wear resistance decreased because of increasing the wear rate by cracking due to low critical stress for crack formation. Furthermore, the H/KIC ratio increased with decreasing the size or volume fraction of retained austenite but decreased when the stacking fault energy of retained austenite became sufficiently high to avoid the formation of twinning and martensite.