When a high-water-cut physical inhibitor (HWPI) is sprayed on the coal in goaf, moisture in coal will undergo a substantial reduction under the influence of liquid flow and water evaporation, which severely weakens the inhibitory effect of the HWPI and greatly shortens its inhibitory lifetime. Therefore, this paper proposes a thermoresponsive secundine inhibitor (TSI) to solve the problem of poor water retention and short inhibitory lifetime by sealing the HWPI in thermoresponsive secundine. Before the ambient temperature (30 degrees C) reaches the trigger temperature, the water retention rate of the TSI is 100%. After the trigger temperature is reached, the TSI will quickly release a large amount of the HWPI to suppress coal spontaneous combustion. The releasing time and trigger temperature of the TSI drop rapidly with the increase of the borehole diameter and borehole number, while its weight loss grows with the increase of the borehole diameter and borehole number. The experimental results reveal that the borehole diameter of 2.5 mm and the borehole number of 12 are the optimal conditions for the TSI to release more HWPI in a relatively short period of time.