Metal-doping is an efficient approach to improve the performance of catalysts, but few researches have been done in applying mixed metals as dopant due to heavy jobs and complex results. In this study, we prepared and evaluated a group of 3-metal-doped nano-TiO2composite photocatalyst (M1-M2-M3/TiO2, M = Cu(II), Mn(II), Zn(II), Co(II), Ni(III), Bi(III)). The prepared catalysts were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the catalysts were evaluated by the degradation of methyl orange (MO) under UV-irradiation. The results showed that Bi-Mn- Zn/TiO2photocatalysts (containing 1.65, 0.41, 0.47 wt% of Bi, Mn, Zn respectively) exhibited the highest removal efficiency (Rt) of 27% for adsorption of MO after 1h in dark and superior photocatalytic activity for degradation of MO, with the highest Rt of 93.03% among all samples after 15 min UV-irradiation. The photocatalytic enhancement of Bi-Mn-Zn/TiO2was attributed to its unique semiconductor composite structure: Bi2O3-MnO-ZnO-TiO2and further proved in batch experiments. Importantly, the as-synthesized M1-M2-M3/TiO2remains stable during the photocatalytic reaction and can be used repeatedly, revealing their promising application in the treatment of organic wastewater.