The　pressure　drops　and　pumping　powers　in　flow　channels　of　proton　exchange　membrane　fuel　cells　are　major　standards　to　evaluate　flow　channel　structures.　Baffled　flow　channels　provide　higher　performance,　while　the　pressure　drop　and　pumping　power　both　aggravate.　In　this　work,　the　impact　of　baffle　leeward　length　on　power　output　and　pressure　drops　of　proton　exchange　membrane　fuel　cells　are　experimentally　studied.　The　pumping　power,　net　power　and　power　efficiency　are　calculated　as　well.　Experimental　results　indicate　that　pressure　drops　increase　when　adding　baffles　in　channels,　and　longer　leeward　lengths　result　in　lower　pressure　drops.　Higher　cell　temperature　results　in　lower　pressure　drops.　The　time　consuming　for　stabilizing　pressure　drop　are　shortened　when　using　baffles　having　longer　leeward　lengths.　The　net　power　is　increased　when　using　larger　baffles,　and　the　highest　net　powers　occur　under　the　temperature　of　333K　or　343K.　In　addition,　raising　the　cell　temperature　can　increase　the　power　efficiency,　and　when　the　leeward　lengths　of　baffles　are　decreased,　the　power　efficiency　is　also　decreased.　When　using　baffle　without　sloping　leeward　sides,　the　power　efficiency　can　be　decreased　to　45.14%　under　lower　cell　temperature　of　323K.