An　Al-based　amorphous　and　nanocrystalline　composite　coating　was　prepared　by　high　velocity　arc　spraying　technique.　It　is　found　from　XRD　and　TEM　analysis　results　that　Al-based　amorphous　and　nanocrystalline　composite　coating　consists　of　amorphous　phases,　nanocrystalline　phases　and　crystalline　phases.　The　coating　has　a　obvious　layered　structure,　and　layer-to-layer　bond　is　good.　It　has　a　compact　structure,　and　no　obvious　crack　and　pore.　Its　porosity　is　about　1.8%.　And　the　average　microhardness　of　the　coating　is　about　311　HV100,　which　can　reach　to　that　of　the　Al-based　amorphous　alloys　prepared　by　traditional　methods.