Graphite felt was modified with polypyrrole by electrochemical oxidation polymerization. The morphology, elemental composition and electrochemical properties of the polypyrrole-modified graphite felts were characterized by SEM, FT-IR, XPS, LSV and EIS. The two-electron oxygen reduction activity of polypyrrole-modified graphite felts were characterized by H2O2 generation rate. The effects of supporting electrolyte and polymerization time on the structure and oxygen reduction performance of polypyrrole-modified graphite felts were investigated. The results showed that nitrogen atoms were introduced to the surface of graphite felts in the form of polypyrrole which greatly enhanced the oxygen reduction activity of graphite felts. Using sodium sulfate as supporting electrolyte led to better two-electron oxygen reduction activity and a H2O2 generation rate up to 24.82 mg/(L·cm2·h) at a cathode potential of -0.45 V. The two-electron oxygen reduction activity of the modified graphite felts increased first and then decreased with the increase of polymerization time. The sample with a polymerization time of 1000 s showed the highest H2O2 generation rate of 29.40 mg/(L·cm2·h). An electro-Fenton system was set up with PPy/GF-Na¬2SO4-1000 as the cathode material to degrade the salty organic wastewater from an ethyl cellulose process. COD of the wastewater was reduced to less than 100 mg/L, with a degradation ratio of 88.8% after 8 hours reaction. No significant activity loss was observed after 6 cycles test.