The effect of Co additive on the microstructural evolusion of WC was investigated. A small amount of Co powder was placed on the top-center of the pure WC powder compact and then sintered at 1950$^{circ}C$. During sintering some abnormally large WC grains of different size and shape observed depending on the distance from the liquid source. However, in the region far away from Co liquid source, it showed low densification and the grains of WC were very small and uniform in size. A small amount of Co liquid phase has a remarkable influence on the AGG of WC and it has been explained in terms of 2-D nucleation and growth mechanism.