In　the　present　study,　a　Fe-based　cored　wire　was　used　to　deposit　coatings　containing　Fe-based　amorphous　phase　and　fine　crystallites　on　a　mild　steel　substrate　by　arc　spraying.　The　micro-structure　and　properties　of　coatings　were　investigated　by　XRD,　SEM,　TEM　and　micro-hardness　meter;　and　the　grain　size　of　the　coatings　was　determined　from　the　corresponding　peak　via　the　Scherrer　formula.　The　experiment　results　show　that　the　coating　has　homogenous　laminated　microstructure　and　contains　only　a　little　micro-pores　and　oxides,　Fe-based　amorphous　phase　and　nanocrystalline　grains　are　observed　in　the　coating,　and　the　grain　size　of　the　crystalline　is　between　10-40　nm.　The　volume　content　of　the　amorphous　phase　in　the　coating　amounts　to　55.3%　by　the　X-ray　diffraction　intensity　curve.　The　coating　is　hard,　with　microhardness　value　about　1260　HV0.1.