In　proton　exchange　membrane　fuel　cells,　baffled　flow　channels　can　enhance　the　reactant　transfer　and　improve　the　cell　performance.　Many　different　baffled　flow　channels　have　been　numerically　studied　in　previous　published　papers.　However,　what　kind　of　baffled　flow　channels　can　improve　the　cell　performance　most　is　still　unknown.　In　this　simulation　work,　a　two-dimensional,　two-phase,　nonisothermal,　and　steady-state　model　of　proton　exchange　membrane　fuel　cells　is　developed.　The　mass　transfer　and　cell　performance　of　PEMFCs　with　different　baffled　flow　channels　have　been　numerically　compared.　Simulation　results　show　that　the　rectangular　baffle　can　enhance　the　reactant　transfer　most　and　improve　the　cell　performance　most;　however,　the　power　loss　in　rectangular　baffled　flow　channel　is　also　the　highest.　To　inherit　the　advantages　and　overcome　the　shortages　of　the　rectangular　baffled　flow　channel,　an　optimized　baffled　flow　channel　is　developed.　In　this　newly　developed　baffled　flow　channel,　the　windward　side　is　designed　as　the　streamline　shape　and　the　leeward　side　is　designed　as　the　sloped　shape.　Results　of　the　simulation　also　show　that　the　optimized　baffled　flow　channel　can　reduce　the　power　loss　accounted　by　the　pumping　power　in　reactant　delivering　process　and　the　cell　performance　can　be　further　improved.