Abstract: Carbon nanotubes (CNTs)/Al₂O₃ composite was fabricated by in-situ chemical vapor deposition growth of CNTs in Al₂O₃ ceramic green body during its sinetering. The results show that multi-walled CNTs have been sucessfully grown and distributed homogeneously in the Al₂O₃ ceramic matrix. The roots of CNTs embed in the Al₂O₃ grains reveal directly growth and firmly combination. The in-situ growth of CNTs in the Al₂O₃ ceramic matrixes requires strictly controlling of the preparation conditions. The CNTs grow at 850℃, while no CNTs are observed in the samples fabricated at higher or lower temperatures. The adding of the pore former, carbon source and catalyst all affect the in-situ growth of CNTs. The entire CNTs/Al₂O₃ composite with densified structure was obtained through subsequent sintering at higher temperature. The CNTs offers the CNTs/Al₂O₃ obviously electrical conductivity up to 3.7 S/m, 13 orders of magnitude higher than that of the bare Al₂O₃. This in-situ growth in preformed ceramic body as one-step strategy is attractive for the development of CNTs/ceramic composites combined with high mechanical and multi-functional properties.