The　geometry　of　the　flow　channel　in　bipolar　plates　(BPs)　significantly　influences　the　performance　of　proton　exchange　membrane　fuel　cells　(PEMFCs).　Considering　this,　the　present　study　is　aimed　at　optimizing　the　flow　field　in　a　straight　channel　by　pursuing　a　minimum　entropy　generation.　In　accordance　with　the　optimization　strategy　established　herein,　the　flow　field　in　a　straight　channel　was　optimized　by　solving　the　governing　equations　using　COMSOL.　Furthermore,　a　novel　M-like　channel　was　designed.　Compared　with　conventional　wave-like　channels,　the　M-like　channel　exhibits　lower　entropy　generation　under　equal　pumping　power,　which　implies　higher　heat　and　mass　transfer　performance.　An　analysis　of　the　four　factors　contributing　to　entropy　generation　revealed　that　the　irreversibility　resulting　from　the　heat　transfer　process　is　higher　than　that　from　its　three　counterparts.　To　further　improve　the　heat　and　mass　transfer　performance　of　the　M-like　channel,　the　effects　of　geometric　parameters　on　the　entropy　generation　were　investigated.　The　polarization　curves　of　the　wave-like　channel　and　M-like　channel　in　a　single　fuel　cell　were　obtained　based　on　the　fuel　cell　and　electrolysis　module.　The　numerical　results　indicated　that　the　maximum　power　density　of　the　M-like　channel　is　higher　than　that　of　the　wave-like　channel　by　21.3%.　These　results　provide　effective　guidance　for　the　geometric　design　of　a　flow　field　in　the　BPs　of　a　PEMFC.