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The effect of medium and coarse WC content on the microstructure and grain distribution of Ni-Co coarse crystalline cemented carbide was studied, and then the effect of grain distribution on the mechanical properties of cemented carbide was discussed. The effect of medium and coarse WC content on the grain size and adjacency of the cemented carbide was analyzed by metallographic analysis, and the distribution pattern of the grains in the microstructure was investigated by using the truncation method; the effects of grain size and grain distribution on the magnetic force, density and other mechanical properties were studied. The results show that the medium and coarse WC grains can be uniformly distributed around the coarse WC grains to hinder the contact between the coarse grains and the bonding phase, which inhibits the rapid coarsening of the coarse grains, reduces the average grain size and average free range of the alloy, and gradually transforms the grain distribution into a bimodal distribution; the relative densities of all the alloys under pressure sintering are above 99.5%, and the bimodal distribution of the grains in the microstructure is verified by the analysis of the coercivity magnetism. The accuracy of the bimodal distribution of grains in the microstructure was verified by the analysis of coercivity magnetism; the decrease of average grain size gradually increased the hardness and decreased the fracture toughness of the alloy; the gradual decrease of super coarse grains in the microstructure was beneficial to the improvement of flexural strength and wear resistance of the carbide. The addition of some medium coarse WC particles to the Ni-Co coarse grain cemented carbide is beneficial to reduce the grain coarsening and thus improve the wear resistance, and the best overall performance is achieved with 30% medium coarse WC particles.