Understanding　the　coupled　mechanisms　between　two-phase　flow　and　reactive　transport　in　proton　exchange　membrane　fuel　cells　is　important　for　improving　cell　performance.　In　this　study,　a　one-dimensional　+　three-dimensional　model　is　developed　to　simulate　the　air-water　two-phase　flow,　mass　transport　and　electrochemical　reaction　in　the　cathode　side　of　proton　exchange　membrane　fuel　cells.　Dynamic　water　behaviors　affected　by　several　forces　in　three　channels　are　well　captured　by　the　volume　of　fluid　method.　Effects　of　liquid　water　behaviors　on　pressure　drop,　mass　flow　rate,　oxygen　concentration　distribution,　current　density　and　especially　the　distribution　characteristics　among　different　channels　are　discussed.　It　is　found　that　the　current　density　increases　under　certain　flow　patterns　such　as　droplet　detachment　and　water　film　on　the　top　wall.　Compared　with　single-phase　flow,　the　two-phase　flow　magnifies　the　flow　maldistribution　in　different　channels,　and　such　maldistribution　in　turn　leads　to　different　water　detachment　sequence　in　the　three　channels.　The　change　of　the　mass　flow　rate　in　the　second　channel　is　more　sensitive　to　that　in　the　third　channel.　Effects　of　the　gas　channel　wall　wettability　and　channel　structures　are　also　investigated.　The　results　show　that　changing　the　gas　channel　as　hydrophobic　will　lead　to　higher　pressure　drop,　lower　current　density　and　poorer　flow　distribution　among　different　channels,　which　thus　is　not　desirable　in　application.　Modified　structures　of　rectangle　channel　and　tapered　channel　are　finally　explored.　Compared　with　the　base　case,　the　tapered　channel　results　in　increased　flow　uniformity　and　averaged　current　density　by　65.9%　and　1.5%,　respectively.