Compared to untreated UHMCFs, the relative content of polaroxygen element gradually increased at the expense of carbon element asthe electrochemical oxidation progressed, which also resulted in a largeextent of increases in the O/C value. When the current density was at3.0 A/m2, the O/C value increased by 353% compared with untreatedUHMCF, which indicated that the oxidized UHMCF surface becamemuch more active. It was also found that the higher the oxidative intensity, the more active carbon fiber surfaces were.