GB/T 5989-2023 specifies the differential temperature rise method for determining the refractoriness-under-load of dense shaped and shaped insulating refractory products, detailing the test principle, sample preparation, operational procedures, and result calculation. It is applicable to the performance testing of such products at temperatures up to 1700°C. The core of the method involves monitoring the deformation and temperature difference of the specimen under constant load and programmed heating to evaluate its resistance to softening under combined high-temperature and load conditions, thereby supporting material selection for high-temperature equipment such as kilns. The test requires instruments such as a refractoriness-under-load tester, a precisely controlled heating furnace, a type B thermocouple, and a vernier caliper to ensure accurate temperature and load control as well as precise deformation measurement. This standard provides a unified technical basis for quality control of refractory materials.