Abstract: Cristobalite was added as the second phase and zircon sand as the mineralizer to the silicon-based ceramic core matrix material, and the ceramic core sample was prepared by hot press injection method. The effect of pre-added cristobalite content on the performance of silicon-based ceramic cores was studied, and the mechanism of the influence of pre-added cristobalite content on the high temperature creep of silicon-based ceramic cores at 1550℃ was analyzed. The results show that as the content of pre-added cristobalite increases, the bending strength and high-temperature deflection of the silicon-based ceramic core gradually decrease, and the porosity of the core gradually increases. When the pre-added cristobalite content is 10wt%, the crystallization rate of quartz glass is the fastest, cristobalite begins to form a high-temperature-resistant cristobalite skeleton, the core’s ability to resist high-temperature deformation is significantly improved, the bending strength is 5.13 MPa, the high temperature deflection is 1.18 mm, the porosity is 40.55%, the comprehensive performance of the ceramic core is the best.