Objective To identify the level and determinants of patient activation in young and middle-aged breast cancer survivors after surgery, and to provide reference for targeted interventions.Methods Using convenience sampling method, 208 patients after breast cancer surgery within 1 year were selected and completed a battery of questionnaires, including a general information questionnaire, the Patient Activation Scale, the Social Impact Scale （to measure stigma）, the Social Support Rating Scale and the Breast Cancer Survivor Self-Efficacy Scale.Results The sample scored （58.10±9.45） for patient activation. Multiple linear regression analysis showed that education level, whether the breast was preserved, stigma, social support and self-efficacy were the influencing factors of patient activation （all P＜0.05）.Conclusion Activation in young and middle-aged breast cancer survivors after surgery is at medium level, and is affected by many factors.Medical staff can lower stigma of patients, and enhance their social support and self-efficacy, to improve patient activation.