Silicon carbide (SiC) ceramics are widely used in critical industries such as aerospace, nuclear energy, chemical processing, and semiconductor manufacturing due to their unique thermal and electrical properties coupled with excellent mechanical properties. Nevertheless, conventional forming methods often fall short when it comes to producing large-sized and complex components. Selective laser sintering (SLS) printing has the advantages of no support, high material utilization, high processing efficiency, etc., endowing it suitable for the precise fabrication of ceramic structural components with complicated shape. Here, the particle grading approach was employed to systematically investigate the impacts of processes such as cold isostatic pressing (CIP), precursor impregnation pyrolysis (PIP), and the combination of CIP with PIP followed by solid-phase sintering at atmospheric pressure. The results revealed that the graded powders significantly enhanced both the bulk density and the flexural strength of the formed body by over 20% compared to non-graded systems. Relative density of the graded system after CIP and subsequent solid-phase sintering at atmospheric pressure was over 90%, confirming successful densification during sintering. In contrast, the non-graded sintered body only achieved a density of 89%. Implementation of the particle grading led to an increase in bulk density, and it was beneficial for achieving higher densification during sintering. Consequently, the flexural strength of the grading-sintered body was significantly improved, reaching 136.8 MPa—a gain of over 37% compared to the non-graded counterpart whose flexural strength was only 99.4 MPa. Meanwhile, high-density SiC ceramics could be achieved by repeating PIP for four cycles combined with solid-phase sintering of which SiC ceramics density was comparable to that of CIP compacts. However, the bulk density of solid-phase sintered body after four PIP cycles was only 2.29 g/cm³, which was accompanied by a flexural strength of 59.6 MPa.