This study investigates numerical modeling of surface generation in microgrinding of ceramic materials by coupled trajectory and finite element analysis. The resultant surface generation from both ductile flow mode grinding and fracture mode grinding is modeled in microgrinding of alumina. In the ductile flow mode grinding, the surface generation is simulated by trajectory analysis. In the fracture mode grinding, the surface generation is estimated from the fully damaged subsurface depth by cohesive zone method (CZM) based FEA simulation. The simulated surface profile matches well with the experimental result in the arithmetic average surface roughness. However, larger error is observed in the root mean squared surface roughness at high feed rate. It is suspected that this is caused by the increased vibration in microgrinding at high feed rate, which increases the complexity in the ground surface.