Temperature　and　heat　flux　inside　proton　exchange　membrane　fuel　cell　(PEMFC)　have　important　effects　on　the　fuel　cell　performance　and　lifetime.　For　real-time　monitor　the　temperature　and　heat　flux　inside　fuel　cell,　we　made　a　thin-film　sensors　by　using　vacuum　evaporation　coating　technology.　The　sensors　were　fixed　on　the　anode　side　of　the　proton　exchange　membrane　fuel　cell,　in-suit　and　simultaneous　measurement　of　temperature　and　heat　flux　variation　with　current　density　has　been　done　under　different　gas　flow.　The　results　show　that　the　temperature　and　heat　flux　inside　fuel　cells　increase　with　the　current　density　during　the　operation　of　fuel　cell,　temperature　rise　more　obviously　when　the　current　density　is　high.　When　current　density　is　low,　heating　rod　has　an　appreciable　effect　on　temperature.　When　current　density　is　high,　heat　of　electrochemical　reaction　dominates　temperature　variation　inside　fuel　cell.　©　2020,　Science　Press.　All　right　reserved.