The utility model relates to a device of high temperature air gap heat -transfer character experimental study carries out, including clearance heat transfer unit (HTU) body, vacuum system, cooling agent water loop and electrical system, clearance heat transfer unit (HTU) body include heating element, be equipped with the heat transfer sleeve outside heating element, the heat transfer sleeve is equipped with the water loop sleeve outward, the water loop of water loop muffjoint cooling agent, the total three -layer of heat transfer sleeve, form two -layer heat transfer air gap between the three-layer heat transfer sleeve, outer heat transfer air gap is used for the controlled temperature, makes the temperature reach test conditions, inlayer heat transfer air gap is for experimental regional. The utility model discloses a design of double -deck air gap guarantees through outside air gap that inboard experimental air gap reaches the linear heat generation rate and the both sides difference in temperature that the laboratory needed. The utility model discloses traditional water -cooled air gap heat -transfer character test device's major structure can be continued to use to the deviceof well adoption, and its economic nature, security and maintainability are superior to the air gap heat -transfer character test device who uses liquid sodium cooling.