Abstract: The effectiveness of color removal for wastewater containing dye by means of chemical oxidation and coagulation has been studied. The effect of oxidants, dosage and pH value on color removal efficiency was investigated, The experimental results show that the mixture of oxidation gases, containing ClO₂,Cl₂，H₂O₂ and O₃ etc., prepared by LC－10A type UV－O₃ chloride dioxide complex disinfector generator, gave better color removal effect than pure ClO₂ prepared by chemical method. The color removal capability of chemical oxidation for reactive dye was superior to that for dispersed dye. The chemical oxidation produced good color removal ratio when the pH value of the solution is less than 10. By means of coagulation, the efficiency of decolorization for dispersed dye was better than that for reactive dye. MgCl₂。6H₂O was shown to be superior to PAC and Al₂(SO₄)₃。18H₂O in color removal for the wastewater. MgCl₂。6H₂O produced excellent decolorization effect in basic aqueous medium (pH≥12.0).