In　the　field　of　measurement,　high-precision　thermocouples　need　higher　precision　calibration　equipment.　However,　the　metal　temperature　equalizing　block　used　in　traditional　thermocouple　calibration　equipment　has　poor　temperature　uniformity,　and　the　structure　of　gas-controlled　heat　pipe　is　complex　and　expensive,　and　the　concentric　annular　heat　pipes　have　high　isothermal　performance　and　simple　structure,　which　can　be　used　to　improve　the　calibration　equipment.　In　this　study,　a　temperature　comparison　source　based　on　potassium　concentric　annular　heat　pipe　was　fabricated　to　replace　the　metal　temperature　equalizing　block,　the　temperature　stability　and　temperature　uniformity　within　0　to　16　cm　of　the　different　metering　wells　at　400　degrees　C,　500　degrees　C,　and　600　degrees　C　were　experimentally　studied.　The　temperature　stability　was　+/-　0.0026　K　and　the　maximum　axial　temperature　difference　within　6　to　10　cm　of　the　metering　well　was　0.027　K.　On　the　vertical　section　of　concentric　annular　heat　pipe,　due　to　the　high　specific　heat　of　liquid　working　fluid,　the　temperature　of　the　metering　well　near　the　bottom　is　higher.