The thick-film metallization of AlN has received considerable attention because of its potential applications in electronic packaging. Here we reported on the thick film metallization of AlN by reactive binders. The metallization paste of Ag was prepared with organic vehicle of castor oil, ethyl cellulose and beta-terpineol and reactive binders of TiB2 and Co3O4. The control of the paste viscosity was discussed by changing the dispersant content. Meanwhile effects of the components and sintering process on the thick film properties were investigated. The properties of metallization film were analyzed with XRD, SEM and electrical test. The adhesion strength and the electrical resistance of the film were 12.7MPa and 5.3mΩ/□ respectively when the paste composition of Ag, TiB2, Co3O4 and the organic vehicle was 72.8%, 1.5%, 0.7% and 25% and the film was sintered in air at 850°C for 15 minutes.