Using Cu(NO3)2•3H2O and Fe(NO3)3•9H2O as raw materials, spinel nano-copper ferrite(CuFe2O4) was prepared by the sol-gel-self-propagating combustion method with the aid of citric acid, and the material was characterized by SEM, EDX, XRD and VSM.The CuFe2O4/persulfate (PDS) system was used to catalytic oxidation treatment of azo dye reactive black 5 (RB5). With the aim to study the effects on catalytic system by the CuFe2O4 dosage, initial PDS concentration, reaction temperature, initial pH, common inorganic anions and humic acid. The results show that the catalytic performance of c-CuFe2O4 prepared by calcination at 300℃ is at the best level. When the temperature at 25℃, the initial concentration of RB5 is 100 mg/L, the dosage of CuFe2O4-300 1 g/L, the initial PDS concentration 8 mmol（1.9 g）/L, and the incipient pH 9.00, the removal rate of RB5 can reach 92.9%. the degradation process follows a quasi-first-order kinetic model. Quenching experiments found that the catalytic sites are on the surface of the material and the pores. The reaction depends on the bivalent/trivalent copper cycle on the surface of the material and the homogeneous catalysis of free Cu2+. SO4-•and •OH are the main active products. CuFe2O4 is super paramagnetic and can be recycled through magnetic separation. After 5 cycles of experiment, it can maintain a removal rate of more than 80%.