Multi-grain diamond grits were prepared through binding micro diamond particles with binder. SEM(Scanning Electron Microscope) was adopted to observe their microscopic morphology, and both multi-grain diamond grits and single diamond grits are made into fixed abrasive pads (FAP). The lapping performance of FAP embedded with multi-grain diamond particles was compared with that with single diamond particles. Results show that the average surface roughness lapped with multi-grain diamond FAP is almost the same as that lapped with single diamond FAP, and the multi-grain diamond FAP shows a higher and more stable material removal rate. The micro-fracture of multi-grain diamond grit in lapping process guarantees the realization of self-conditioning of hydrophilic FAP. In addition, the subsurface damage depth of quartz glass lapped with multi-grain diamond FAP is much smaller, which is only about 1/2 of that with single diamond FAP.