Abstract: In situ reinforcement of ceramic matrix can be achieved by the elongated grains or platelets in situ formed in matrix during sintering through the mechanisms of crack bridging, crack deflection, elongated grain/platelet pullout, etc. In this work, in situ Al₂O₃ platelet/Ce-TZP composites and in situ SrO·6Al₂O₃ rod-like grain/Ce-TZP composites were prepared by adding AlOOH together with the mineralizer of TiO₂ or the reactant of SrCO₃ to Ce-TZP matrix. The microstructure of the composites was observed by SEM, and the density and mechanical properties of the composites were measured. The results indicated that TiO₂ markedly promoted the anisotropic grain growth of Al₂O₃ and SrCO₃ reacted with Al₂O₃, forming Al₂O₃ platelets and anisotropic SrO·6Al₂O₃ rod-like grains respectively. The in situ Al₂O₃ platelets and SrO·6Al₂O₃ rod-like grains were well-distributed in the matrix with a larger aspect ratio. Sintering temperature obviously affected the grain size and the content of Al₂O₃ platelet and SrO·6Al₂O₃ rod-like grain. The mechanical properties of the composites were improved by in situ introduction of Al₂O₃ platelets and SrO·6Al₂O₃ rod-like grains.