Stereolithography (SL) based additive manufacturing technology facilitates fabricating structurally complicated silicon-based ceramic cores. However, SL fabricates ceramic component by layer-by-layer solidification of ceramic slurries. The instability of ceramic slurries often leads to the phenomenon of ceramic particle gradient distribution in the prepared ceramic component, which can damage the mechanical properties, porosity, and dimensional accuracy of ceramic component, hindering the application of SL in the preparation of ceramic component. Herein, we systematically investigated and optimized such impacting factors, including particle size distributions, addictive (nanopowder) and solid loading, which result in appropriate viscosity and high stability of SiO₂ ceramic slurries. A SiO₂ ceramic slurry for SL showed the viscosity (26.1 Pa·s) and after 264 h sedimentation time with 80 wt.% of solid loading. Using the slurry, we prepared a ceramic with a shrinkage rate maintained below 4%, a porosity of 21.56%, and a flexural strength of 20.53 MPa.