Based on the first-principles plane wave ultrasoft pseudopotential method, the geometric structure of (6, 0) single-wall aluminum nitride nanotubes, Ag doped, and Ag-O co-doped nanotubes were optimized.This work discusses the energy band structure, density of states and differential charge density of aluminum nitride nanotubes before and after doping. The results show that the band gaps of intrinsic AlN nanotubes, Ag doped AlN nanotubes and Ag-O co-doped aluminum nitride nanotubes are 2.49 eV, 1.84 eV and 1.80 eV. All doping configurations still preserve semiconductor characteristics. Based on the present discussion, the top of the valence band of Ag doped AlN nanotubes penetrates through the Fermi level to form a degenerate state, which realizes the p-type doping of AlN nanotubes. However, there is a strong hybrid effect between the electronic orbitals of Ag-4d state and N-2p state,the mono-doping of Ag is in general energetically unfavorable. After O doping, Ag and O attracts each other to overcome the repelling of acceptor Ag atoms, which makes the doping of Ag in AlN nanotubes more stable; the band gap of co-doped nanotube system is narrower than that of single doped nanotube system, and the conductivity is further enhanced. Ag-O co-doping is expected to be an effective method to obtain p-type AlN nanotubes.