Highlights•Rail grinding experiments were conducted using whole abrasive wheels and a single abrasive grain.•Wear mechanisms of abrasive wheel for rail grinding were revealed.•Attrition wear, micro-fracture, macro-fracture and pulling-out of grain successively became the primary wear mode.•The grinding wheel in the wear state of grain fracture had the optimum grinding performance.Facing grinding by abrasive wheel is the most widely used method to maintain the rails. The wear of abrasive wheel is inevitable and influences the grinding performance significantly. Therefore, a deep understanding on the wear mechanisms of abrasive wheel is beneficial for the development of grinding wheels and optimization of grinding processes. In the present study, rail grinding experiments were conducted using whole abrasive wheels and a single abrasive grain. The wear mechanisms of abrasive wheel were revealed, including the attrition wear, fracture and pulling-out of abrasive grains, material adhesion, clogging, and chemical wear. With the degradation of abrasive grain, the attrition wear, micro-fracture, macro-fracture and pulling-out of grain successively became the primary wear mode as the function of service time. With the primary wear state changing from attrition wear to grain fracture and grain pulling-out, the grinding efficiency was improved, but the grinding quality was decreased. The grinding wheel in the wear state of grain fracture had the optimum grinding performance.