Al-doped ZnO nanowire arrays were synthesized with Au catalysis on Si(100) substrate using the chemical vapor deposition technique. Only (002) diffraction peaks of ZnO can be found in the XRD patterns of the samples, which shows that the as-grown nanowires are highly crystalline in nature and grow along the ［001］ direction. The SEM images show that the ZnO nanowires are perpendicular to the substrate surface. Room-temperature photoluminescence (PL) measurement shows 3 near band-edge emission peaks at 373, 375 and 389nm. Analysis shows that the band gap of Al-doped ZnO nanowaires is 3.343eV and the exciton binding energy is 0.156eV. Room-temperature PL spectrum of pure ZnO nanowaires shows 3 near band-edge emission peaks at 377, 379 and 389nm. The band gap of pure ZnO nanowaires is 3.301eV and the exciton binding energy is 0.113eV, which shows that the band gap increases due to Al doping.