The effects of nitrogen substitutional doping in Stone-Wales (SW) defect on the electronic structure and the optical property of single-walled nanotube are simulated by using the density functional theory based on the first-principles. It is found that the system energy reduces and binding becomes stabler, and the nitrogen in SW produces a semi-full band near the Fermi level in which the electron effective mass varies with the changing of the position of nitrogen. The absorption and the reflectivity weakened obviously and absorption and reflection peak are both redshifted in the lower energy region. There is a distinct peak at the energy less than 11eV.The results are discussed theoretically. The nitrogen doping and SW defect of carbon nanotubes are expected to provide a theoretical basis for the photoelectric material applications.