The　sensor　elements　based　on　GaN　high　electron　mobility　transistor　(HEMT)　have　considerable　advantages　on　sensitivity,　response　speed,　detection　surface,　and　harsh　environment　adaptability　because　of　the　features　of　HEMT,　such　as　high　2DEG　density　at　the　hetero-interface,　wide　band　gap,　high　breakdown　voltage,　stable　chemical　properties,　and　high　electron　mobility.　In　this　paper,　the　structures,　mechanism,　progress　of　work,　advantages　and　disadvantages　about　the　two　mature　types　of　sensors　developed　from　GaN-based　HEMT　basic　structure　are　discussed　and　summarized　firstly.　Then,　the　latest　progress　on　three　kinds　of　nevel　GaN-based　HEMT　sensors　is　reviewed　in　detail　focusing　on　the　device　material　and　the　optimization　of　gate　structure　and　material.　Among　them,　GaN-based　HEMT　photodetector　is　highlighted　in　the　aspects　of　the　material　system,　key　process,　detector　structure,　principle　and　new　mechanisms.　Finally,　the　future　direction　for　the　development　of　GaN-based　HEMT　sensor　elements　is　explored.　©　2016,　Science　Press.　All　right　reserved.