Abstract: Objective To explore the effect of group psychological intervention on psychological disturbance and upper extremity exercise in patients with breast cancer undergoing radical mastectomy. Methods A total of 120 patients with radical mastectomy from June to August 2019 in our hospital were selected as control group, given routine psychological intervention, while 120 radical mastectomy patients from September to November 2019 were selected as observation group, given group psychological intervention. The cognitive status of the disease, the degree of psychological disturbance and condition of upper limb exercise before and after the intervention were compared. Results The scores of uncertainty, complexity, unpredictability and lack of information in the observation group were significantly lower than those in the control group(P<0.05). The negative mood score of the observation group was significantly lower, the positive psychological score was significantly higher, and the total score was significantly lower than those of the control group(P<0.05). The superior rate of upper limb function in the observation group was higher than that in the control group, and the rate of upper limb edema was lower than that in the control group, and the differences were statistically significant(P<0.05). Conclusion Group psychological intervention can improve cognition level of breast cancer patients after radical mastectomy, alleviate their psychological disturbance, promote effect of their upper extremity functional exercise, and reduce the occurrence of upper extremity edema.