Objective: To explore the effect of gratitude-expansion theory behavior on the fear of recurrence of breast cancer chemotherapy patients. Methods: A total of 154 breast cancer patients who were treated in Affiliated Hospital of Yangzhou University from January 2018 to December 2019 were selected as the research objects, and they were divided into groups A1, A2, B1, and B2 according to their disease stages. Group A1 was stage I and stage II patients undergoing routine behavioral guidance intervention; group A2 was stage I and stage II patients undergoing gratitude-expension theoretical behavioral guidance intervention; group B1 was stage III and stage IV patients undergoing conventional behavioral guidance intervention; group B2 was stage III and IV patients undergoing gratitude-expansion theoretical behavior guidance intervention. The disease-free survival rate, overall survival rate, local recurrence rate and distant metastasis rate of patients in group A1 and group A2 after surgery were compared, and patients’ cancer recurrence fear was evaluated by using the fear of progression questionnaire-short form (FoP-Q-SF); the progress of cancer lesions after chemotherapy was compared between patients in groups B1 and B2, and the FoP-Q-SF was used to evaluate their fear of cancer recurrence. Results: The A1 and A2 groups were followed up for 6 months after the operation. The disease-free survival rate and overall survival rate of the A1 and A2 group was not statistically significant (P>0.05). The disease progression of patients in groups B1 and B2 after treatment was analyzed. In group B2, the disease remission rate after chemotherapy was 75.00%, and the disease control rate was 93.18%, which was significantly higher than that of the control group. The difference was statistically significant (P<0.05). The postoperative FoP-Q-SF score in group A1 was (30.63±4.01), and the postoperative FoP-Q-SF score in group A2 was (27.37±4.32); the postoperative FoP-Q-SF score in group B1 was (32.33±5.34). The postoperative FoP-Q-SF score in group B2 was (29.45±4.27). Differences between groups were statistically significant (PA, PB<0.05). Conclusion: Gratitude-expansion theoretical behavior can reduce the fear of recurrence in patients undergoing breast cancer chemotherapy , improve the rate of disease control of patients with treatment, and help patients adjust their mentality to fight the disease with a positive and optimistic attitude.