The　flow　field　design　is　an　effective　measure　to　improve　hydrothermal　management　within　a　fuel　cell.　This　paper　proposes　a　staircase　flow　channel　used　in　the　oxygen-side　flow　channel　of　a　unitized　regenerative　fuel　cell.　Based　on　a　two-dimensional　two-phase　non-isothermal　model,　the　hydrothermal　distribution　variation　induced　by　staircase　channels　with　different　step　numbers　is　investigated　in　detail.　Results　show　that　oxygen　transport　is　boosted　and　liquid　water　accumulation　is　reduced　in　the　fuel　cell　mode　with　the　use　of　staircase　structures,　thus　local　oxygen　starvation　under　high　current　density　is　alleviated.　In　addition,　the　temperature　uniformity　of　electrodes　is　effectively　improved,　and　the　fuel　cell　net　power　is　enhanced　by　up　to　14.24%　at　0.2　V　with　a　five　-step　flow　channel.　In　electrolytic　cell　mode,　however,　the　advantage　of　downward　staircase　structures　is　not　prominent.　Therefore,　a　counter-flow　method　is　suggested　during　the　mode　switching　stage,　which　can　improve　average　current　density　by　up　to　10.83%.　Besides,　round-trip　energy　efficiency　is　introduced　to　evaluate　the　comprehensive　performance.　The　staircase　flow　channel　coupled　with　counter-flow　method　improves　the　effi-ciency　of　unitized　regenerative　fuel　cell　by　up　to　49.63%　under　high　current　density,　compared　with　conven-tional　flow　channels　with　co-flow　configuration.