The invention discloses a method for smelting preparation of high-quality boron carbide crystals to overcome the defects of the current boron carbide smelting technique and current products and meet the requirement of the sapphire industry for high-quality boron carbide. The method comprises the steps of breaking a carbonaceous reducing agent and a catalyst into powder independently; taking boric acid powder, carbonaceous reducing agent powder and catalyst powder according to the weight ratio, adding a proper amount of water for blending, conducting stirring, and then pressing the mixture on a high-pressure ball presser into lumps; drying the pressed lumps, and placing the dried lumps in a submerged arc furnace to be smelted, so that large boron carbide crystals are prepared; breaking the large boron carbide crystals into small pieces, and then conducting classification, so that the high-quality boron carbide crystals are obtained. The raw material utilization rate is high, production cost is low, energy is saved, the raw material volatilization rate is low, dust pollution is reduced greatly, the produced boron carbide has high purity, hardness and density, the high-quality boron carbide yield is high, and the requirement for sapphire grinding can be totally met.