Anthraquinone dye Reactive Blue (KN-R) is first selected as the model dye to test the treatment of UV-vis/Ferrioxalate/H2O2 system. The effect of parameters Fe2+/H2O2, pH and H2C2O4 are synthetically assessed. The optimum concentration is obtained at 1:15 of Fe2+/H2O2 and 30mg·L-1 of H2C2O4 at pH=3.0 in 30min. Under the optimum condition, the removal rate of color, chemical oxygen demand (COD) and total organic carbon (TOC) are more than 99%, 87.7% and 66.8% respectively. The results show that the reaction accorded with a pseudo-first-order and the degeneration velocity of KN-R is 0.2459[dye](mg·L-1/min).