Rapid densification of a SiC powder with additive 0.5 wt% $B_4$C was conducted by spark plasma sintering (SPS). The unique features of the process are the possibilities of using very fast heating rate and short holding time to obtain fully dense materials. The heating rate and applied pressure were kept to be $100^{circ}C$/min and 40 MPa, while sintering temperature and soaking time varied to 1800, 1850, 1900 and $1950^{circ}C$ and 10, 20 and 30 min, respectively. All of the SPS-sintered specimens at $1950^{circ}C$ reached near-theoretical density. The XRD found that 3C-to-6H transformation at $1850^{circ}C$. The microstructures of the rapidly densified SiC ceramics consisted of duplex microstructure with ultrafine equiaxed grains under 2 $mu extrm{m}$ and elongated grains of 0.5∼2 $mu extrm{m}$ wide, length 3∼10 $mu extrm{m}$. The biaxial strength increased with the increase of sintering time. Strength of 392.7 MPa was obtained with the fully densified specimen sintered at $1950^{circ}C$ for 30 min, in agreement with the general tendency that strength increases with decreases pore. On the other hand, the fracture toughness shows the value of 2.17∼2.34 MPa$.$$m^{1/2}$ which might be due to the transgranular fracture mode.