Proton　exchange　membrane　fuel　cells　use　hydrogen　as　fuel　and　directly　convert　the　chemical　energy　into　electricity.　Electrochemical　reaction　rate　is　non-uniform　inside　the　cell.　So　the　step-wise　non-uniform　distributions　of　platinum　and　carbon　loading　in　cathode　catalyst　layer　are　optimized　to　obtain　higher　cell　output　performance.　The　optimal　distributions　with　and　without　constrains　along　gas　flow　direction,　vertical　flow　direction　and　thickness　direction　are　explored.　Then,　current　density　change　is　analyzed　to　obtain　a　group　of　parameter　to　be　suited　to　more　operation　voltages.　The　results　show　that　the　parameters　obtained　and　cell　performance　change　under　each　optimization　voltage　is　various.　In　the　results　with　constrains,　carbon　distribution　is　better　for　cell　performance　improvement　among　these　three　directions.　The　best　structure　for　increasing　cell　performance　is　the　carbon　distribution　along　Z-Axis.　More　platinum　or　carbon　loading　is　good　for　cell　performance,　mainly　because　more　loading　can　provide　a　larger　electrochemical　surface　area　and　reduce　oxygen　transfer　resistance.　In　the　results　without　constrains,　the　platinum　or　carbon　loading　reaches　to　upper　bound.　Carbon　distribution　is　more　favorable　to　improve　cell　performance　than　platinum,　and　the　current　density　can　be　improved　at　least　6.644　%　compared　with　base　case.　For　better　output　performance　and　considering　operation　voltage　instability,　the　carbon　loading　obtained　along　Z-Axis　at　0.5　V　of　optimization　voltage　can　be　used　for　catalyst　layer　fabrication.　©　2023　Elsevier　Ltd