The invention discloses a three-layer composite structure radar-wave absorbing powder and a method of preparing the same. The radar absorbing powder has a three-layer composite structure; the core portion is carbon tube or carbon fiber; the intermediate layer is monodisperse nano-iron or nickel particles; the outermost layer is amorphous iron; the outer layer is coated with polyimide film. The preparing method comprises the steps of: taking natural fiber carbide or carbon nano-tube as carrier, taking iron oleate or acid nickel as reactant and preparing the intermediate product through carrier absorbing, pyrolysis and hydrogen reduction; taking the intermediate product as carrier, malysite as reactant, forming radar absorbing powder having three-layer composite structure by hydrogen reduction, polyimide coating. Substrate of the powder belongs to electrically lost absorbing material; the intermediate layer is paramagnetic absorbing material; the outer layer is superparamagnetic absorbing material; and the powder has the advantages of highly efficient, light and absorbing frequency bandwidth and is suitable for producing various coating and structural radar stealth material, especially suitable for radar stealth of various aerial crafts.