Objective To investigate the level of perceived cognitive function in Chinese breast cancer patients on endocrine therapy, and to explore the influencing factors. Methods A total of 366 breast cancer patients were included in the cross-sectional study, and filled out the demographic questionnaire, Functional Assessment of Cancer Therapy-Cognitive Scale (FACT-Cog), Pittsburgh Sleep Quality Index(PSQI), International Physical Activity Questionnaire(IPAQ), Hospital Anxiety and Depression Scale (HADS) and Functional Assessment of Chronic illnesses Therapy-Fatigue (FACIT-Fatigue). Results The total cognitive function scores averaged (108.46±16.20) points. Multiple linear regression analysis showed that, age, previous hormone replacement therapy, sedentary time, fatigue, anxiety and daytime dysfunction were the main factors affecting cognitive function of breast cancer patients（P<0.01 for all）. Conclusion Clinical workers should pay attention to the change of cognitive function of breast cancer patients during endocrine therapy. Intervention measures which aim at alleviating fatigue and anxiety, shortening the sedentary time, reducing daytime dysfunction, are helpful to improve patients′ cognitive function level.