Extraordinarily-coarse grain hard alloy and preparation method thereof

The invention relates to an extraordinarily-coarse grain hard alloy and a preparation method thereof. The extraordinarily-coarse grain hard alloy comprises the following effective raw materials of tungsten carbide powder with the average grain size being 30-45 [mu]m, cobalt powder with the average grain size being 2-4 [mu]m, tungsten powder with the average grain size being 2-3 [mu]m, ethyl alcohol with the purity being 99.8% or above, and powdery paraffin with the melting point being 52-54 DEG C; the weight proportion of the part, with the grain size being smaller than 5 [mu]m, in the tungsten carbide powder is smaller than or equal to 1%, the purity of the tungsten carbide powder is 99.8% or above, the oxygen content of the tungsten carbide powder is 0.03% or below, the iron content of the tungsten carbide powder is 0.03% or below, the content of combined carbon in the tungsten carbide powder is 6.02%-6.04%, and the content of free carbon in the tungsten carbide powder is 0.06% or below; the purity of the c