Paralled flaw precipitation method has been employed to synthesize nanostructured Bi2O3. It is found that the bandgap and photocatalytic performance of Bi2O3 has a strong dependence on the kind of precipitants. The prepared photocatalysts were characterized by BET, XRD, UV-Vis diffuse reflectance and SEM. The results show that Bi2O3 prepared by NH3·H2O has the highest BET surface area, pore volume, the smallest pore size and the particle average size. Bi2O3 prepared by NH3·H2O exhibits the best photocatalytic activity. The results of further experiments show that bandgap and the specific surface area all play an important role in promotion of photocatalytic activity of Bi2O3 prepared by NH3·H2O.