A novel geopolymer concrete is developed, incorporating waste ceramic aggregates, with ultra-high residual strength after exposure to elevated temperatures. Different aggregate volume fractions and particle size gradations are designed, and the variations in mass loss, volume shrinkage, compressive strength, mineral composition, and microstructure of geopolymer mortar after exposure to high temperatures ranging from 20 ℃ to 1000 ℃ are investigated by testing mass loss, volume change, strength, XRD and SEM. The results show that the waste ceramic aggregate (WCA) applied in the preparation of geopolymer mortars improve the mechanical properties and high-temperature resistance. By optimizing aggregate particle size gradation, the microstructure of the geopolymer mortar becomes denser and more homogeneous, and the high-temperature resistance is further improved. The residual compressive strength at 1000 °C is 115.2 MPa, 476 % higher than that of reference. These findings demonstrate the great potential of geopolymer mortars using ceramic aggregates with optimized gradation for high temperature resistant applications.