Grounded in the framework of Action Theory, this study investigates the linguistic patterns and expressive strategies used by elderly patients to describe pain in rehabilitation clinic settings. A detailed analysis of clinical conversation data reveals three predominant modes of pain description. The responsive mode is marked by 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 everyday life memories, reconstructing pain experiences within imagined contexts. The metaphorical mode transforms abstract pain sensations into concrete and perceptible imagery, offering distinctive linguistic expressions. Together, these modes form a composite speech act that serves both informational and interactional functions, directly shaping the quality of doctor-patient communication and clinical decision-making. In addition, the study examines the difficulties observed in elderly patients’ use of these three types of pain descriptions and the potential cognitive factors influencing them. This research provides a new theoretical lens for understanding elderly patients’ pain narratives and offers practical implications for enhancing medical communication and optimizing pain management in geriatric care.