The regulatory mechanisms of nitric acid oxidation and γ-methacryloxypropyltrimethoxysilane(KH570)silane grafting on the performance of porous carbon and the performance of proton exchange membrane fuel cell(PEMFC)cathode microporous layers are investigated.The pore structure,conductive network and interfacial properties of the microporous layer are regulated by surface modification and compounding design.Compared with the unmodified porous carbon,oxygen-containing functional groups are introduced by nitric acid oxidation,by which the Brunauer-Emmett-Teller(BET)specific surface area and pore volume are increased by 6.4％and the median particle size(D50)is decreased by 36％.An organic layer is formed by KH570 silane grafting,by which the BET specific surface area and pore volume are reduced by 73％and the D50 is reduced by 8.6％.Microporous layers are prepared from nitric-acid-modified porous carbon,unmodified porous carbon and Vulcan XC-72 carbon black,respectively.It is shown by electrochemical impedance spectroscopy(EIS)results that,compared with the microporous layer made of unmodified porous carbon,the charge transfer resistance(Rct)of the nitric-acid-modified carbon layer is reduced by 26.2％;when KH570-modified porous carbon is compounded with unmodified porous carbon,the Rct of the resulting microporous layer is further reduced by 21.0％compared with that of the nitric-acid-modified carbon layer.It is revealed by SEM analysis that a hierarchical pore structure is constructed by the compounding design,this microporous layer exhibits the lowest charge transfer resistance and the best discharge performance.