Nanometer alpha-alumina powder was synthesized using the pore rich activated carbon as the reaction place, and the alpha-alumina nanopartide reinforced nickel based composite coating was prepared by flash thermal spray method. The composite coating was abraded on abrasive wear-machine to study its wear resistance property. The results showed that a large number of uniform size spherical-shaped precursor particles were in the activated carbon pores, which could be long-term stable in a spherical shape and adsorbed on the pore wall. In addition, activated carbon pores could prevent the alumina particles from growing up and reuniting effectively during the precursor particles calcination process. And the activated carbon had completely burned at high temperature as well. Finally, nano alpha-alumina powder with good dispersion was obtained. The wear resistance of the nickel based composite coating was reinforced by the nanometer alpha-alumina powder. With 2% volume fraction addition of nanometer alpha-alumina, the coating has the best abrasive wear resistance property. (C) 2014 Elsevier B.V. All rights reserved.