Abstract: Oriented TiO₂ nanosheet arrays with tunable doping concentration of oxygen vacancies were successfully fabricated via sodium borohydride liquid-phase reduction method，and were investigated as the photocatalyst for the degradation of methyl orange（MO）.The results show that the photocatalytic activity of the oxygen-deficient nanosheet arrays could be significantly improved，and the optimal photo degradation rate for MO degradation was achieved to be 0.6 h^-1，about 1.5 times higher than that of the unreduced nanosheet arrays.These promising results would be attributed to the combination of their oriented sheet-like morphology and a suitable doping concentration of oxygen vacancies，which can increase redox site of photocatalytic reaction，expand the light absorption range，and improve the conductivity.