The grinding mechanism is the base of developing new precision machining technology, especially for brittle materials including ceramics. In previous work, many results were gained from single grit cutting model in which a grit is in contact continuously with a workpiece, similar to the indentation or scratching process, to model the material remove in grinding processing. However, the abrasives are distributed randomly on the surface of the grinding wheel, and they will impact the workpiece periodically in the grinding process. In this study, the discrete element method was introduced to simulate the mechanics behavior of Al2O3Al2O3 ceramic. The model was validated by simulating indentation test. Both linear scratching test and pendulum scratching test have been simulated in this paper to model the grinding process. The cracks initiation and propagation were also investigated. This study has demonstrated that we should pay close attention to pendulum scratching test to explore the grinding mechanism, and concentrate on cracks initiation and propagation.