The invention belongs to the technical field of shaping of boron carbide powder and particularly relates to a preparation method of boron carbide with high tap-density. The preparation method of boroncarbide with high tap density, provided by the invention, comprises the following steps: grinding the boron carbide raw material for 5-10h under the condition of 60-90r/min to obtain fine boron carbide of which the D50 is 40-55 microns; and performing two-sided grinding on the obtained fine boron carbide in the presence of water under the conditions that the two-sided grinding pressure is controlled to be 40-60g/cm<2> and the two-sided grinding time is controlled to be 60-80min, thereby obtaining boron carbide of which the tap-density is 1.40-1.45g/cm<3>.