The invention discloses a pyramidal silicon carbide ceramic absorber and a preparation method thereof. Particularly, the pyramidal silicon carbide ceramic absorber is prepared from the following components in percentage by weight: 40-60% of SiC, 5-15% of SiO2, 15-20% of MgO, 0-10% of BaCO3, 0-3% of MnO2, 0-2% of CoO, 0-2% of V2O5, 0-2% of Al2O3, 5-10% of semi-refined paraffin wax and 1-5% of PE (polyethylene) plasticizer. The preparation method comprises the following components: carrying out high-temperature compounding, carrying out injection molding to obtain pyramids, degreasing and sintering to obtain the final product. The pyramidal ceramic absorber with broadband absorption property prepared by the injection molding process has the characteristics of simple technique, stable properties, favorable heat conductivity coefficient, high hemispherical emittance, high vacuum applicability and the like.