A　composite　coating　was　fabricated　on　pure　magnesium　by　hydrothermal　treatment　in　order　to　reduce　its　degradation　in　body　environment.　The　coating　was　characterized　by　scanning　electron　microscopy　(SEM)　and　X-ray　diffraction　(XRD).　The　XRD　pattern　showed　that　the　main　composition　of　the　coating　was　a　mixture　of　CaSiO3,　MgSiO3　and　Mg(OH)(2).　Electrochemical　test　showed　that　the　corrosion　current　density　(i(corr))　of　the　coated　magnesium　was　decreased　by　about　two　orders　of　magnitude　compared　with　that　of　the　bare　magnesium,　and　the　EIS　measurement　also　showed　that　the　corrosion　resistant　performance　of　the　coated　magnesium　was　significantly　enhanced.　Meanwhile,　weight　loss　test　showed　that　the　weight　loss　of　the　coated　magnesium　was　lower　than　that　of　the　bare　magnesium.　Hence,　the　present　study　indicated　that　the　composite　coating　could　greatly　slow　down　the　degradation　of　pure　magnesium.