Current market sales holding furnace for aluminum casting production process using the thermowell is made of silicon carbide materials tubular, its high thermal expansion coefficient,poor thermal stability, thus easily lead to casing breakage, short service life, and due to structural defects to make the thermocouple dislocation, the temperature control is not accurate. The products in the structure, the casing is arranged at one end of the clamping head, the other end of the positioning sleeve is sheathed, design of fixed tube in the casing cavity plug, the thermocouple is fixed and accurate positioning, eliminate the gap between the thermocouple and the sleeve, prevent the furnace body heat release, the thermocouple temperature channelingcaused by inaccurate the problem; in material and workmanship, preparation technology of high performance ceramic structure, using the transformation toughening mechanism, developed a high nitrogen compound ceramic thermocouple tube of high quality, which has the advantages ofgood thermal stability, no explosion and long service life etc.. Can be customized according to customer requirements.