Grounded in the framework of Action Theory, this study investigates the linguistic patterns and expressive strategies used by older patients to describe pain in rehabilitation clinic settings. This research aims to provide a new theoretical perspective on how older patients express pain and offer practical implications for enhancing medical communication and optimizing pain management in geriatric care. An in-depth analysis of clinical conversation data identifies three primary modes of pain description. The responsive mode primarily occurs in response to vagueness and difficulty in symptom localization, often influenced by age-related cognitive decline and the complexity of chronic pain. The retrospective-situational mode relies on the activation of memories of daily lives to reconstruct pain experiences within specific imagined contexts. The metaphorical mode transforms abstract pain sensations into specific and perceptible imagery, offering distinctive linguistic expressions that are intended to be understandable to physicians. In addition, the study discusses the difficulties older patients encountered in describing these three types of pain and the potential cognitive factors influencing them. For example, the difficulties older adults experience in vocabulary retrieval and narrative construction during pain description may be associated with declines in executive function and theory of mind abilities.