Silicon carbide (SiC)-zirconium diboride ($ZrB_2$) composites were prepared by subjecting a 60:40 vol% mixture of ${eta}$-SiC powder and $ZrB_2$ matrix to spark plasma sintering (SPS) in 15 $mm{Phi}$ and 20 $mm{Phi}$ molds. The 15 $mm{Phi}$ and 20 $mm{Phi}$ compacts were sintered for 60 sec at $1500^{circ}C$ under a uniaxial pressure of 50 MPa and argon atmosphere. Similar composites were simulated using $Flux^{(R)}$ 3D computer simulation software. The current and power densities of the specimen sections of the simulated SiC-$ZrB_2$ composites were higher than those of the mold sections of the 15 $mm{Phi}$ and 20 $mm{Phi}$ mold simulated specimens. Toward the centers of the specimen sections, the current densities in the simulated SiC-$ZrB_2$ composites increased. The power density patterns of the specimen sections of the simulated SiC-$ZrB_2$ composites were nearly identical to their current density patterns. The current densities of the 15 $mm{Phi}$ mold of the simulated SiC-$ZrB_2$ composites were higher than those of the 20 $mm{Phi}$ mold in the center of the specimen section. The volume electrical resistivity of the simulated SiC-$ZrB_2$ composite was about 7.72 times lower than those of the graphite mold and the punch section. The power density, 1.4604 $GW/m^3$, of the 15 $mm{Phi}$ mold of the simulated SiC-$ZrB_2$ composite was higher than that of the 20 $mm{Phi}$ mold, 1.3832 $GW/m^3$. The $ZrB_2$ distributions in the 20 $mm{Phi}$ mold in the sintered SiC-$ZrB_2$ composites were more uniform than those of the 15 $mm{Phi}$ mold on the basis of energy-dispersive spectroscopy (EDS) mapping. The volume electrical resistivity of the 20 $mm{Phi}$ mold of the sintered SiC-$ZrB_2$ composite, $6.17{ imes}10^{-4}{Omega}cm$, was lower than that of the 15 $mm{Phi}$ mold, $9.37{ imes}10^{-4}{Omega}{cdot}cm$, at room temperature.