Objective To explore the effect of online structured group psychological intervention on negative emotions and perceived social support among postoperative breast cancer patients. Methods Totally, 73 postoperative breast cancer patients were randomly divided into 2 groups.On the basis of conventional nursing care, the control group (n=37) partook in online lectures on diseases and mental health, while the intervention group (n=36) was subjected to an online structured group psychological intervention program.Before and after the intervention, the patients were evaluated for anxiety, depression, and social support levels.The intervention group was additionally surveyed for their appraisal of the activities they had joined in. Results After the intervention, scores of anxiety and depression in the intervention group were significantly lower than those in the control group, while scores of social support were significantly higher in the former than the latter group (P＜0.05,P＜0.01); 94.44% of the intervention group patients were satisfied with the online structured group psychological intervention program. Conclusion Online structured group psychological intervention could effectively improve the negative emotions of postoperative breast cancer patients and enhance their perception of social support.