In order to solve the problems which the DDNP wastewater is difficult to be microbial degraded, the electro-Fenton process was used for treating DDNP wastewater, finding out the best experimental conditions. The results show that when the electrolytic time is 3.5h, the pH is 4, dosage of H₂O₂(30%) is around 10ml/L, and the electrolysis voltage is 12V, then, the COD removal rate can be up to 97.24%, and chroma removal rate can be up to 93.75%.