GaN　high　electron　mobility　transistor(GaN　HEMT)　has　high　channel　electron　concentration,　high　electron　mobility　and　high　breakdown　voltage,　which　makes　it　have　great　development　prospects　in　high　frequency,　microwave　and　other　fields.　In　the　development　of　GaN　HEMT,　suppressing　current　collapse　has　always　been　the　focus　and　difficulty　of　research.　Based　on　SILVACO　TCAD　simulation　software,　the　current　collapse　suppression　by　field　plate　structure　is　studied　and　discussed　in　this　paper.　Firstly,　the　model　of　enhanced　GaN　HEMT　device　is　established　and　its　correctness　is　verified.　Then,　the　phenomenon　of　current　collapse　and　virtual　gate　model　are　introduced.　From　the　theory　of　improving　breakdown　voltage　of　device　by　field　plate　structure　as　the　starting　point,　field　plate　structure　is　added　to　the　device　model　and　simulation　experiments　are　carried　out.　According　to　the　results,　the　principle　of　suppression　current　collapse　by　field　plate　structure　is　analyzed,　and　the　correctness　of　virtual　grid　model　is　verified.　©　2019　IEEE.