Abstract: The ESR dating method could date the samples within a time span from hundreds of years to millions of years. However, the average lifetime of ESR signals from deep-sea carbonate rocks are relatively shorter. In this regard, the age limit of the deep-sea carbonate rocks dating need to be further studied. In this paper, we studied the thermodynamic characteristics of ESR dating signals acquired from old deep-sea carbonate rocks and the average lifetime of those deep-sea carbonate rocks is estimated. The results of the thermodynamic properties of deep-sea carbonate suggests that the single first-order kinetic equation might not be suitable to calculate the average lifetime, and the double first-order kinetic equation is more effective. The average lifetime of the deep-sea samples we calculated is about 5.14×10⁶ years by using the double first-order kinetic equation. Thus the estimated age is 320±50 ka, which is in good agreement with the unbalanced U system dating result of 365±49 ka.