LaPO4 was added to Al2O3 ceramic matrix to improve the machinability of the composites. Different from the traditional way of making Al2O3/LaPO4 composite, coating method is introduced. In the present work, LaPO4-coated α-Al2O3 powders were synthesized through the heterogeneous precipitation method and sintered into Al2O3/LaPO4 composites by pressureless sintering at 1600°C for 2h. The phase components and microstructure of Al2O3/LaPO4 composites are presented according to variations of lanthanum phosphate (LaPO4) content (10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%). From the TEM image, it can be seen that the coated powders have a clear core-shell structure and the thickness of the coating varies from 5 to 15 nm approximately. X-ray diffraction analysis showed that only Al2O3 and LaPO4 phases exist in the Al2O3/LaPO4 composites which indicated that there is good chemical compatibility between Al2O3 and LaPO4 phase. Microstructure development of Al2O3/LaPO4 composites has been explored by SEM, the coating structure became less recognized after sintering, layered and fiber shaped LaPO4 was obviously observed in the Al2O3/LaPO4 composites with the increase of LaPO4 addition. The LaPO4 inhibited grain growth of Al2O3 by distributing at the Al2O3 grain boundaries. The weak interface of Al2O3/LaPO4 and layered soft LaPO4 phase can be responsible for the machinability of the composites.