The invention relates to a method for measuring the expansion times of a continuous casting tundish covering agent. The method is characterized by comprising the following steps: (a), a covering agent sample is measured through a sample measuring device and sealed in a sample bag; (b), a thermal property tester is selected as a sample tester, a furnace body of the tester is heated to 1400 DEG C, and the temperature is kept constant for 30-40 min; (c), the covering agent sample is placed in a hearth quickly, the covering agent sample is placed flat, and a heat supply system of the tester is switched off after the constant temperature of 1400 DEG C is kept for 40 minutes; (d), when the temperature of the tester falls to 600 DEG C, a test system is closed; (e), the height of the covering agent sample is measured at the positions 50mm away from four diagonal corners of the hearth and at the center of the hearth, namely, five positions are chosen for obtaining test data all together, the average value of the test data is obtained, the height of the original sample is divided by the average value, and the obtained result is the expansion times of the covering agent. The method for measuring the expansion times of the continuous casting tundish covering agent has the advantages of being rapid, simple, convenient, good in data reliability and reproducibility, and capable of truly reflecting the expansion conditions of the tundish covering agent on a molten steel surface, thereby providing guidance for producers and users of the continuous casting tundish covering agent.