GaN　field-effect　transistors　(FET)　enables　low　conduction　loss　and　low　switching　loss　in　high-frequency　(＞MHz)　resonant　wireless　power　transfer　systems.　In　this　work,　a　GaN　magnetic　resonant　wireless　power　transfer　(WPT)　system　with　75%　efficiency　was　designed　and　built.　Advantages　of　GaN　magnetic　resonant　wireless　power　transfer　technology　are　introduced　and　the　principle　of　magnetic　resonant　wireless　power　transfer　technology　is　explained.　Then,　LTspice　is　used　to　simulate　the　designed　system.　Moreover,　a　GaN　based　wireless　power　transfer　testing　system　was　built　and　tested,　the　results　of　which　indicate　that　both　the　coil　coupling　coefficient　k　and　the　load　of　the　system　affect　the　transmission　efficiency　of　the　system.　In　addition,　it　is　found　that　the　increment　of　input　and　output　power　will　also　increase　the　efficiency　of　the　system.　The　system　is　further　improved　according　to　the　actual　application,　the　system　can　provide　power　for　both　lamp　and　mobile　phone.　©　2019　IEEE.