Experiments with ten groups of limestone specimens (four samples per group) under ten specific temperatures, 25 °C, 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C, show that the high-temperature effect on the elastic modulus of rocks conforms to thermoelastic responses with a quadratic temperature function. The thermal damage factor can be reduced, by ignoring the effect of Poisson's ratios and densities, to simply a ratio of the P-wave velocities before and after high-temperature treatments. Based on the collected experimental data, we correlate the P-wave velocities change rate with both the peak compressive strength and effective solid matrix. It demonstrates that the high-temperature effect on the thermal damage factor can be directly expressed as the rate of change in the peak compressive strength and effective solid matrix. All these properties (thermal damage factor calculated by the P-wave velocity, peak compressive strength, and effective solid matrix) share a similar exponential trend with increasing temperature. The rates of change in the elastic modulus, P-wave velocity, peak compressive strength, and effective solid matrix also exhibit a similar powerful trend with increasing temperature. This study provides insight into the detailed characteristics of thermal damage related to the mechanical property of limestones exposed to high temperature.