The　temperature　stability　of　standard　resistors　plays　an　important　role　in　assuring　the　accuracy　of　resistance　measurements　that　use　resistance　ratio　bridges　to　calibrate　standard　platinum　resistance　thermometers　(SPRTs)　on　the　International　Temperature　Scale　of　1990　(ITS-90).　Therefore,　during　resistance　measurements,　the　resistors　are　always　kept　in　temperature　controlled　oil　or　air　baths　and　enclosures　to　maintain　a　constant　temperature.　In　order　to　achieve　better　temperature　stability　and　reduce　the　effects　of　temperature　fluctuations　on　the　resistance　of　a　standard　resistor,　an　annular　water　heat　pipe　thermostat　immersed　in　a　mineral　oil　bath　was　developed　to　accommodate　and　stabilize　a　standard　resistor.　Also,　the　thermostat＇s　performance　was　characterized.　The　results　showed　that　the　temperature　stability　of　standard　resistors　was　within　1　mK　after　using　the　heat　pipe　thermostat　compared　with　that　of　30　mK　for　the　oil　bath.　Therefore,　the　temperature　stability　of　standard　resistors　was　improved　by　more　than　one　order　of　magnitude,　which　was　attributable　to　the　good　thermal　self-regulating　abilities　of　the　water　heat　pipe.