Power　supply　for　Unmanned　Aerial　Vehicle　(UAV)　low　voltage,　high　current　output,　so　conventional　diode　rectifier　circuit　had　been　unable　to　meet　the　high　efficiency　in　switching　power　supply,　which　should　selected　synchronous　rectification　(SR).　But　conventional　gate　charge　retention　drive　existed　dead　time　and　constant　drive　voltage　problems.　In　this　paper,　proposes　a　new　gate　charge　retention　drive　to　improve　the　phenomenon.　Using　Saber　to　analysis　the　two　methods,　we　could　verify　the　accuracy　of　the　theory.　Finally,　72v　input　6v/20　output　forward　converter　are　designed　using　the　new　methods　and　90%　efficiency　is　achieved　at　full　load.