The rare earth-chitosan composite flocculant was used for treating dyeing wastewater, the treatment process and optimum processing conditions were discussed.The influences of the concentration of rare earth - chitosan, pH value and temperature on turbidity, COD removal rate and decolorization rate were studied.By orthogonal experiment in combination with single factor experiment method, the results showed that the optimum treatment conditions were that  the concentration  of  rare  earth - chitosan composite flocculant was 1.5 g/L, pH value was 9, temperature was 35 ～ 45 ℃.