Porous lanthanum doped alumina ceramic composite was prepared by self-organization and solid-state reaction between Al₂O₃ and La₂O₃. Crystal phases, microstructure and density of ceramics were examined to characterize novel composites in the system of Al₂O₃ and La₂O₃. After heat treatment at 1300°C and 1400°C, LaAl₁₁O₁₈ plate-like crystals were formed through the solid-state reaction of LaAlO₃ with Al₂O₃. The addition of large amounts of La contributed to the increase of LaAl₁₁O₁₈ plate-like crystals and their cross-linking microstructure. The porous alumina composites maintained high surface areas of 20 m²/g after heating at 1300°C, and 11 m²/g at 1400°C. The bending strength of La added alumina composite was 57 MPa after heating at 1400°C.