Microstructure,　microhardness　and　thermal　stability　of　pulse　electrodepositied　nanocrystalline　Ni-Co-Fe-P　alloy　coating　were　studie　by　means　of　XRD,　TEM,　EDS,　DSC　and　microhardness　tests.　The　results　show　that　the　nanocrystalline　Ni-40.41%Co-6.16%Fe-1.63%P　coating　with　FCC　structure　exhibits　(111)　texture　with　a　grain　size　of　8.8　nm　approximately.　The　microhardness　of　Ni-Co-Fe-P　alloy　coating　increases　as　annealing　temperature　increases　and　reaches　a　peak　value　between　300°C　and　450°C,　and　then　it　decreases　gradually　with　further　increasing　annealing　temperature.　The　grain　grows　up　to　35.1　nm　after　annealing　at　450°C　and　160.8　nm　after　annealing　at　600°C.　During　annealing　the　texture　of　the　coating　changes　from　(111)　to　(200).　The　DSC　curve　shows　that　the　coating　begins　to　exotherm　at　474.4°C　and　reaches　the　peak　at　temperature　of　499.1°C.　The　exothermic　ΔH　is　9.086　J/g.　According　to　the　Kissinger　equation,　the　activation　energy　of　grain　growth　for　the　coating　was　worked　out,　which　is　369.3　kJ/mol,　showing　high　thermal　stability.