Mixtures of WC-Co containing 6% and 9%wt cobalt and having variable particles size of 8nm, 50nm and 3.5mm were selected for sintering by spark plasma sintering (SPS). The starting powder of WC with a particle size of ~3.5mm was ball milled for intervals of 3 hours for up to 72 hours yielding WC with 8nm average crystallite size. Later, pre-milled WC powders were ball mixed for 18 hours with cobalt. All sizes of powders, 8nm, 50nm and 3.5mm were sintered in SPS at the temperature of 1150°C and 1250°C for 10 minutes by applying uniaxial pressures of 50 and 75 MPa. Sintering parameters were optimized by examining densification and microstructural observations. Sintered samples were studied by XRD, SEM, and hardness testing. It was observed that optimizing the parameters of SPS has a crucial role in increasing the densification percentage of the final product and slightly affects the hardness values.