Objective: To discuss the effect of health education based on protection motivation theory in three aspects of postoperative breast cancer patients, including adherence of limb functional exercise, function of limb shoulder joint and self-efficacy. Methods: We selected 96 cases of radical mastectomy patients treated in our department for the study by using convenience sampling. The patients were divided into two groups with random number table method, including an observation group and a control group, with 48 patients in each group. Postoperative patients in the control group received routine health education, while postoperative patients in the observation group received health education based on protection motivation theory on the basis of the control group. Observed the limb functional exercise compliance, the limb shoulder joint function and the self-efficacy of patients in two groups, 3 months after discharged from hospital. Results: Three months after discharged from hospital, the exercise adherence rates in the observation group was 97.87%, which was significantly higher than that in the control group (84.78%); the shoulder joint complete recovery rate in the observation group was 95.74%, which was significantly higher than that in the control group (82.61%); the total score of self-efficacy, the score of positive attitude, self-determination, and self-decompression were all higher than those in the control group, the differences were statistically significant (P<0.05). Conclusion: Health education based on protection motivation theory can improve the functional exercise adherence, limb shoulder joint function and the self-efficacy of breast cancer patients. It is worthy of promotion use.