Objective To explore the influencing factors of the preoperative frailty perception in elderly patients undergoing knee replacement, and to provide a reference for developing targeted intervention programs.Methods A descriptive qualitative study was designed, and 16 elderly frail patients scheduled for knee replacement were selected using purposive sampling method, then semi-structured interviews were performed and directed content analysis was used to analyze the interview data based on the frailty integration model.Results A total of 4 themes and 11 sub-themes were refined:physiological dimension (age-related functional decline, persistent symptom distress, multimorbidity), psychological dimension (negative emotions and depletion of psychological capital), social dimension (insufficient social activities, lack of parent-child interaction, personal emotional retention and expressive difficulty), environmental dimension (increased health risks due to cold climate, limited accessibility to medical resources, and economic pressure).Conclusion The preoperative frailty perception in elderly patients undergoing knee replacement is influenced by physiological, psychological, social, and environmental factors.Healthcare professionals can develop and implement preoperative frailty prehabilitation programs based on these influencing factors, so as to effectively enhance their preoperative stress resistance ability and improve postoperative outcomes.