Objective:Based on the theory of planned behavior (TPB), the exercise intervention program for breast cancer patients undergoing chemotherapy was constructed, and its application effect was preliminarily explored.Methods:A total of 116 patients receiving chemotherapy in the department of breast surgery from June to December 2021 in Shanxi Provincial Cancer Hospital were selected by purpose sampling method. The subjects were randomly divided into control group and experimental group by flipping a coin. The control group was given routine nursing, and the experimental group was given routine nursing on the basis of exercise intervention based on the theory of planned behavior. After three cycles of chemotherapy, the effects of the intervention were evaluated by piper Revised Fatigue Scale (RPFS), Exercise Self-efficacy Scale and Quality of Life Core Scale (EORTC QLQ-C30).Results:In the intervention stage, there were 2 cases in the experimental group and 3 cases in the control group lost. After the intervention, the total score and all dimensions (behavioral, emotional, sensory and cognitive) of cancer-induced fatigue in the experimental group were (2.30 ± 0.58), (2.21 ± 0.85), (2.32 ± 0.70), (2.66 ± 0.71) and (2.03 ± 0.58), which were lower than those in the control group (2.84 ± 0.44), (2.79 ± 0.60), (3.04 ± 0.75), (3.04 ± 0.60) and (2.53 ± 0.56), the differences were significant ( t values were 3.05-5.23, all P<0.05). The total scores of exercise self-efficacy and the dimensions of physical, psychological and social environment were higher than those of the control group ( t values were -7.63 - -3.31, all P<0.05). The scores of overall quality of life, physical function and emotional function were higher than those of the control group ( t = -3.48, -3.14,-2.34, all P<0.05), while the scores of fatigue and insomnia symptoms were lower than those in the control group ( t = 5.13, 3.14, both P<0.05). Conclusion:The exercise program based on the theory of planned behavior can improve the exercise self-efficacy of breast cancer patients undergoing chemotherapy, reduce cancer-related fatigue and improve their quality of life.