Silicon carbide with 50 mass% zirconia ceramic matrix composites were processed by Mechanical Milling (MM) followed by Spark Plasma Sintering (SPS). By controlling the parameters of MM and SPS, an ultra-fine ZrO2 grain was homogeneously dispersed and refined on the surface of a fine SiC powder, forming 2 a harmonic microstructure. The mechanical properties and the densification behavior of the SiC-ZrO2 composites were investigated. The effects of the milling time on the microstructure and on the mechanical properties of the composite are discussed. The results indicate that the composite mechanically milled for 144 ksec and sintered at 1773 K had the highest relative density of 98% along with a bending strength of 1128 MPa and a fracture toughness of 10.7 MPa.m 1/2. These superior mechanical properties were influenced by the microstructure characteristics such as the homogeneous grain dispersion. Thus, the grain refinement forming harmonic microstructure can be considered a remarkable design tool for improving the mechanical properties of SiC-ZrO2 as well as other ceramic composite materials.