Clean and economical techniques are in urgent need for improving antibiotics removal from wastewater. In this study, a multi-stage bio-contact oxidation reactor (BCOR) was constructed and further enhanced by electrochemistry to treat sulfamethoxazole (SMX) wastewater. The stimulatory effects of the electrochemistry were investigated together with the succession of microbial communities as well as the possible conversion pathways of SMX. The results showed that the SMX and chemical oxygen demand removal rates reached up to 92.96 ± 0.62 % and 91.42 ± 0.82 % at electric current density of 2.0 mA/cm2. Electrochemistry enhancement induced bone cleavage and oxidation transformation pathways of SMX while reduced the toxicity of degrading intermediates. Moreover, electrochemistry enhancement stimulated the growth of Klebsiella and Rhodobacter as well as the fermentation, chemoheterotrophy and aerobic_chemoheterotrophy functions which further promoted the SMX removal. This study revealed the biochemical removal mechanisms of SMX degradation and manifested the feasibility of combing electrochemistry with BCOR to treat antibiotics wastewater with low energy consumption.