As a non-steroidal anti-inflammatory drug, diclofenac, was commonly used as analgesic, antiarthritic and antirheumatic, and has frequently been detected in municipal wastewater treatment plants (MWTPs) effluents and demonstrated to be potentially environmental risk on human beings. In the present study, N, S co-doped TiO2 nano-crystallites decorated TiO2 nano-tube arrays (N, S-TiO2 NCs/TiO2 NTAs) photoelectrode was used to degrade diclofenac containing wastewater. In addition, the effects of some critical parameters including initial pH, external positive potential, sodium sulfate concentration and initial diclofenac concentration on the photoelectrocatalytic (PEC) degradation of diclofenac containing wastewater and dynamic characteristics were investigated systematically. Results showed that N, S-TiO2 NCs/TiO2 NTAs photoelectrode exhibited high PEC efficiency for the degradation of diclofenac, in which the PEC processes fitted well with the Langmuir–Hinshelwood (L–H) model. Furthermore, external additional anions such as Cl–, ClO– and NO3 – played an important role in inhibiting the degradation of diclofenac. Also, the N, S-TiO2 NCs/TiO2 NTAs photoelectrode possessed good stability for consecutive applications for degradation of diclofenac, which could potentially be utilized in wastewater treatment.