Na+doped WO3 nanowire photocatalysts were prepared by using post-treatment(surface doping) and in situ(bulk doping) doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradiation, the results showed that 1 wt.% Na+bulk-doped WO3 performed better, with higher photoactivity than surface-doped WO3. Photoelectrochemical characterization revealed the differences in the photocatalytic process for surface doping and bulk doping. Uniform bulk doping could generate more electron–hole pairs, while minimizing the chance of electron–hole recombination. Some bulk properties such as the bandgap, Fermi level and band position could also be adjusted by bulk doping, but not by surface doping. Na + doped WO3 nanowire photocatalysts were prepared by using post-treatment (surface doping) and in situ (bulk doping) doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradiation, the results showed that 1 wt.% Na + bulk -doped WO3 performed better with higher photoactivity than surface-doped WO3. Photoelectrochemical characterization revealed the differences in the photocatalytic process for surface doping and bulk doping. Uniform bulk doping could generate more electron-hole pairs, while minimizing the chance of electron-hole recombination. Some bulk properties such as the bandgap, Fermi level and band position could also be adjusted by bulk doping, but not by surface doping.