Fluxgate　sensors　are　key　devices　for　magnetic　field　surveys　in　geophysics.　In　areas　such　as　deep　drilling,　fluxgate　sensors　may　have　to　operate　steadily　at　high　temperatures　for　a　prolonged　period　of　time.　We　present　an　accordant　ring-core　type　fluxgate　sensor　that　is　stable　up　to　220(degrees)C.　The　high　temperature　consistency　is　achieved　by　using　an　Fe-based　nanocrystalline　magnetic　core,　PEEK　structural　components,　an　epoxy　resin　wrapping,　as　well　as　a　broadband　short-circuited　working　mode.　The　sensor　was　characterized　at　various　temperatures　up　to　220　degrees　C　by　evaluating　impedance,　hysteresis,　permeability　and　sensitivity.　We　found　a　sensitivity　of　approximately　24　kV/T　at　25(degrees)C　with　an　acceptable　temperature　coefficient　of　742　ppm/C-degrees　throughout　the　range.　The　variation　law　of　magnetic　characteristics　and　their　influence　mechanism　on　output　amplitude　and　phase　are　discussed.