An ethanol water (CH3CH2OH-H2O) system was designed to synthesize alpha-Bi2O3 microrods by a mild and one-step solvothermal method in the presence of surfactant dodecylamine (C12H27N). X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS) were employed to characterize the structure and morphology of the samples. The photocatalytic activity of alpha-Bi2O3 microrods was evaluated by the degradation of Methyl Orange (MO) under visible-light irradiation (lambda > 420nm), which was up to 90% within 4 h.