Installing　blocks　in　cathode　flow　field　can　effectively　enhance　the　transfer　of　oxygen　from　channel　to　the　reaction　sites　of　catalyst　layer,　thus　boosting　the　performance　of　the　fuel　cell.　In　this　work,　an　optimization　methodology　combined　with　genetic　algorithm　and　three-dimensional　fuel　cell　modeling　is　developed　to　optimize　the　design　of　partially　blocked　channel　for　a　proton　exchange　membrane　fuel　cell　(PEMFC)　with　parallel　flow　field.　In　the　optimization,　the　heights　of　the　blocks　are　assumed　to　be　linearly　increased　and　two　parameters　(i.e.,　height　of　the　first　block　and　the　height　increase　between　adjacent　blocks)　are　considered.　The　impact　of　the　optimized　design　of　the　blocked　channel　on　cell　performance　is　analyzed,　and　the　effects　of　the　optimized　blocked　channel　designs　with　increasing-height　and　uniform-height　block　height　distributions　were　also　compared　in　detail.　With　this　optimization　methodology,　the　optimal　height　distribution　of　the　blocks　in　the　channel　can　be　obtained　for　various　block　numbers.　With　varying　the　block　numbers,　the　cell　voltage　and　net　cell　power　are　firstly　improved　until　the　maximal　values　reached　and　then　lowered.　The　maximal　net　cell　power　is　reached　for　the　block　number　of　16.　As　compared　with　the　flow　channel　without　adding　blocks,　the　net　power　of　the　PEMFC　can　be　enhanced　by　about　10.9%.　For　pressure　drop　behavior,　with　the　optimized　block　height　distribution,　the　total　pressure　drop　in　cathode　flow　field　can　be　maintained　in　similar　level　with　varying　block　numbers　from　4　to　20.　Considering　both　the　net　power　and　pressure　drop,　the　optimized　blocked　channels　with　adding　8　to　16　blocks　are　recommended　in　this　study.　Besides,　it　is　indicated　that　the　performance　of　the　optimized　block　design　with　increasing-height　is　higher　than　that　of　the　optimized　block　design　with　uniform-height.　©　2020　Hydrogen　Energy　Publications　LLC