Objective To explore the heterogeneity of psychological reactions in young and middle-aged breast cancer patients after surgery, and analyze the predictive effect of self-compassion and perceived partner responsiveness on the trajectories. Methods Based on prospective research design, 247 young and middle-aged breast cancer patients who met the criteria were selected from February 2021 to August 2022. The self-designed general information questionnaire, the Psychological Reaction Scale for Breast Cancer Patients，the Perceived Partner Responsiveness Scale and the Self-Compassion Scale were used for follow-up survey at four time points: before postoperative chemotherapy, after the first chemotherapy, during chemotherapy and after chemotherapy. The latent growth mixture model was used to identify the trajectories. Results There were three different change trajectories in the psychological reactions of young and middle-aged breast cancer patients after surgery, named as moderate delayed decline group (61.13%), low psychological reactions group (23.89%) and high-risk continuous remission group (14.98%). Multiple logistic regression analysis showed that the influencing factors of psychological reaction trajectories included surgical methods, self-compassion, and perceived partner responsiveness (all P<0.05). Conclusion The psychological reactions of young and middle-aged breast cancer patients after surgery had different change trajectories. Surgical methods, self-compassion and perceived partner responsiveness could predict the psychological reaction trajectories. Medical staff should strengthen psychological intervention for young and middle-aged patients with breast cancer, and formulate effective intervention programs according to the trajectory type.