Commercial　fuel　cell　stacks　often　have　a　large　electrode　area　to　obtain　a　high　power　output.　Uniformity　in-plane　distribution　of　vital　physical　quantities　plays　a　key　role　in　improving　cell　performance　and　avoiding　degradation.　In　this　study,　a　three-dimensional　two-fluid　multiphase　model　is　adopted　to　analyze　the　in-plane　distribution　characteristics　of　key　parameters　(reactant　concentration,　temperature,　local　current　density,　and　membrane　water　content)　for　a　large-scale　PEMFC　with　an　active　area　larger　than　300　cm2.　The　particular　feature　of　the　PEMFC　studied　is　that　there　are　gap　zones　near　the　edge　between　the　bipolar　plate　and　gas　diffusion　layer　and　membrane.　The　results　show　that　for　the　structure　without　gap　zones,　the　cell　performance　improved　by　about　1%.　The　non-uniformity　of　cathode　reactant　distribution　is　generally　higher　than　that　of　the　anode;　The　non-uniformity　of　temperature　in　the　x　direction　is　higher　than　that　in　the　y　direction　(flow-direction).　With　the　increase　of　average　current　density,　the　temperature　in　the　membrane　increases,　and　the　membrane　dehydrates　gradually.　The　flow　direction　of　coolant　has　a　significant　impact　on　the　cell　performance.　When　coolant　is　in　the　same　direction　as　hydrogen,　the　cell　performance　decreases　by　about　3.75%　at　0.8　A/cm2.　©　2022