Objective To explore the mediating role of patient power distance in the relationship between health literacy and medication safety behavior among elderly patients with chronic diseases, and to provide a basis for developing relevant nursing interventions. Methods A total of 296 elderly patients with chronic diseases were surveyed using the General Information Questionnaire, the Health Literacy Management Scale, the Patient Power Distance Scale and the Inpatients′ Involvement in Medication Safety Scale (IIMSS). Results The elderly patients with chronic diseases scored an average of (96.51±25.57) points in health literacy, (40.05±14.60) points in power distance, and (80.85±22.92) points in participation in medication safety behavior. Health literacy of the elderly patients with chronic diseases was negatively correlated with power distance of the patients, positively correlated with participation in medication safety behavior, and power distance was negatively correlated with participation in medication safety behavior (all P<0.05). Structural equation modeling results showed that health literacy of the elderly patients with chronic diseases could positively predict medication safety behavior, and patient power distance had a partial mediating effect between health literacy and medication safety behavior, with the mediating effect accounting for 31.88% of total effect. Conclusion Patient power distance plays a mediating role between health literacy and medication safety behavior among elderly patients with chronic diseases. Medical staff should improve health literacy of elderly patients, pay attention to patient power distance, and improve their participation in medication safety behaviors.