Abstract: To explore the effect of grinding parameters on surface quality and the mechanism of material removal mode in lapping process, lapping experiment on Si₃N₄ bearing balls was carried out by vertical grinder. And the lapping process was designed according to different speeds of lapping panel and lapping pressure. The surface morphology was examined using SEM and 3D optical microscopy and the FEM simulation was combined to analyze the material removal mode and the surface quality in the grinding process. The results indicate that the speed of lapping panel and the lapping pressure have great influence on the removal mode, surface defect and surface quality of ceramic balls during lapping. With the decrease of speed of lapping panel and pressure, the surface defects such as scratches, pits and snowflakes are obviously reduced, and the surface quality is improved accordingly. The material removal mode is mainly 2-body abrasion when the lapping load and speed are high, and 3-body abrasion at low lapping load and speed. Compared with two-body abrasion, the subsurface cracks by three-body abrasion are deeper.