Gallium　nitride　(GaN)　and　its　family　of　materials　(including　GaN,　InN,　AlN　and　their　alloys)　are　known　as　the　third　generation　of　semiconductor,　which　has　important　applications　in　optoelectronics　and　microelectronics.　In　the　structure　of　GaN-based　high　electron　mobility　transistor　(HEMT)　device,　there　is　a　relatively　large　conduction　band　offset　in　the　AlGaN/GaN　heterojunction　structure,　and　it　can　produce　a　strong　spontaneous　and　piezoelectric　polarization　effect　in　the　vicinity　of　the　heterojunction,　which　can　also　accumulate　high　concentrations　of　two-dimensional　electron　gas　(2DEG)　under　the　condition　of　no　need　of　intentionally　doping　at　the　interface.　The　surface　of　Heterojunction　AlGaN/GaN　interface　will　form　a　2DEG　channel,　and　the　2DEG　in　potential　well　is　controlled　by　the　gate　voltage,　also　the　2DEG　layer　is　very　close　to　the　surface,　which　is　sensitive　to　the　state　of　the　surface.　When　the　surface　state　changes,　it　can　cause　a　change　in　the　2DEG　density,　thus　the　concentration　of　2DEG　can　be　adjusted　by　changing　the　surface　states,　thereby　changing　the　current　between　the　source　and　drain.　GaN-based　HEMT　serves　as　a　gate　control　device,　which　has　a　high　concentration　of　2DEG　and　is　sensitive　to　the　surface　state　at　the　AlGaN/GaN　heterojunction.　According　to　the　basic　structure　and　advantages　of　the　GaN-based　HEMT　device,　the　ferroelectric　thin　film　PZT　is　deposited　on　the　metal　gate　serving　as　a　light　sensitive　layer.　When　the　light　is　incident　on　the　gate,　the　photo-sensing　layer　PZT　generates　the　photovoltaic　effect,　which　causes　the　surface　charge　of　the　photosensitive　layer　to　change,　and　also　causes　the　2DEG　to　change,　so　the　input　current　changes.　In　this　paper,　firstly,　a　new　＂M/F/M/S＂　structure　is　proposed　by　introducing　a　photosensitive　material　PZT　on　a　GaN-based　HEMT　gate　electrode　and　combining　the　PZT　of　a　ferroelectric　thin　film　with　photovoltaic　effect.　Secondly,　the　HEMT　device　is　fabricated　on　the　AlGaN/GaN　epitaxial　wafer　of　sapphire　substrate,　and　the　photosensitive　unit　PZT　is　prepared　on　the　gate,　and　thus　the　HEMT　device　with　photosensitive　is　realized.　Finally,　the　carrier　concentration　in　the　channel　is　regulated　by　the　photovoltaic　effect　of　PZT　and　365　nm　UV　and　visible　light　are　detected　through　changing　the　source-drain　current.　The　comparative　tests　under　the　conditions　with　and　without　a　photosensitive　gate　HEMT　device　show　that　when　the　voltage　V-gs　is　smaller,　the　saturation　drain-source　current　I-ds　measured　under　the　irradiation　of　visible　light　in　the　former　condition　is　not　reduced　compared　with　that　in　the　latter　condition,　and　the　increment　of　I-ds　measured　in　the　former　condition　is　5.2　mA　larger　than　in　the　latter　condition.　Therefore　it　can　be　seen　that　the　PZT　can　act　on　the　gate　GaN-based　HEMT　device　under　the　irradiation　of　visible　and　ultraviolet　light　and　adjust　the　channel　current.