Objective: To construct a network model of symptom clusters and unmet needs in breast cancer patients during surgery and postoperative chemotherapy, identify the core symptom clusters and key areas of unmet needs, as well as the predictive relationship between the two, providing scientific guidance for improving patients' symptom experiences and meeting their reasonable care needs. Methods: From May to December 2025, using convenience sampling, 350 newly diagnosed breast cancer patients visiting a tertiary hospital in Yinchuan, Ningxia, were selected as survey subjects. Follow-up surveys on symptoms and unmet needs were conducted on the 3rd and 14th days post-surgery, and before, during, and after chemotherapy. Data were analyzed using partial correlation networks and cross-lagged networks. Results: Ultimately, 350 breast cancer patients completed the follow-up surveys. Exploratory factor analysis and partial correlation networks indicated that there were five symptom clusters during treatment: disease-related behavioral symptom cluster, psychological and emotional symptom cluster, limb discomfort symptom cluster, gastrointestinal symptom cluster, and body image symptom cluster, with fatigue showing high centrality at all five time points. Cross-lagged network analysis further showed that there was a complex interaction between core symptom clusters and unmet needs at different treatment stages. Health information needs and emotional needs always remained the core needs during treatment. The limb discomfort symptom cluster, as the core symptom cluster in the early postoperative stage, mutually predicted the need for treatment information; the psychological and emotional symptom cluster and body image symptom cluster, as the core symptom clusters during chemotherapy, could predict rehabilitation information needs and emotional needs. Conclusion: This study confirmed that core symptom clusters differ at different treatment stages in breast cancer patients, and there is a complex interaction with unmet needs. Dynamically assessing the interaction between core symptom clusters and core needs is crucial for optimizing symptom management during treatment. In the future, healthcare professionals can use this information to construct a "cycle-adapted" symptom and needs support program targeting core symptom clusters, providing a reference for alleviating patients' discomfort during treatment and meeting their reasonable care needs.