[Purposes] The clarity of the thermodynamic process of underground cavern is an important basis for the safety design and operation scheduling of compressed air energy storage (CAES) plants. [Methods] In view of the existing thermodynamic model of underground cavern has the shortcomings in calculating heat exchange, which has large heat loss in the high-pressure storage stage and excessive heat replenishment in the low-pressure storage stage. On the premise of a comprehensive analysis of the rationality of the theoretical basis of the thermodynamic model for underground cavern, the root causes of the deviations in the heat calculation are analyzed, the improvement methods are proposed and the rationality of the improved models are verified through 3 cases. [Findings] The results show that the existing analytical model of thermodynamic calculation ignores the uneven temperature distribution of CAES underground gas storage during operation, causing distortion of the convective heat transfer model between the cavern wall and the compressed air, which is the root cause of the temperature calculation error. The problem of excessive temperature calculation deviation in the air storage stage can be better solved by the mixed convective heat transfer model. [Conclusions] The results of several analytical cases prove the rationality of the improved model proposed in this paper, which can provide a calculation basis for the volume optimization design and efficiency analysis of CAES underground gas storage.