The invention discloses a 
gallium nitride power device with a multi-field plate structure. The 
gallium nitride power device is sequentially provided with a substrate, a nucleating layer, a buffer layer, a 
first insertion layer, a first GaN layer, a second 
insertion layer, a second GaN layer, an AlGaN 
barrier layer, a 
passivation layer, a grid 
electrode field plate, a drain 
electrode field plate, aprotective layer, a grid 
electrode insertion layer, a p-type GaN grid electrode, a grid electrode 
metal, a source electrode 
metal and a drain electrode 
metal from bottom to top, wherein the 
passivation layer located on the surface of the AlGaN 
barrier layer is in a strip shape arranged at intervals, the grid electrode field plate and the drain electrode field plate respectively cover part of thepassivation layer, and the surfaces of the grid electrode field plate and the drain electrode field plate and the space between the grid electrode field plate and the drain electrode field plate are covered with the protective layer. According to the invention, the 
electric field distribution is uniform, the 
voltage endurance capability of the device is enhanced, the stability of grid electrode turn-on 
voltage and grid electrode 
voltage of the device is effectively improved, and the electric leakage of the device under the action of large current is effectively reduced. The preparation methodis completely compatible with a traditional process, and the preparation difficulty is low.