To observe and evaluate the effects of Sanyin Formula on cognitive impairment related to chemotherapy for triple negative breast cancer(TNBC).Methods:A prospective cohort study was carried out for 130 TNBC patients receiving chemotherapy at Longhua Hospital affiliated to Shanghai University of Traditional Chinese Medicine and Fudan University Shanghai Cancer Center from December 2020 to June 2021.According to receiving Sanyin Formula or not after chemotherapy，the patients were assigned into a control group(n=64) and an observation group(n=66).The control group received conventional treatment，and the observation group received Sanyin Formula after chemotherapy.The drug was taken warm after meals for 3 months.After treatment，the FACT-cog score，neuropsychological test results，TCM symptoms，and safety indicators of the patients were recorded.Results:After follow-up，there were 49(79.03%) and 47(75.81%) patients with cognitive abnormalities in the control and observation groups，respectively.The relative risk of exposure factors was 0.93.The improvement of quality of life in the observation group was different from that in the control group(all P<0.05).In the control group，only the quality of life was improved，while the other symptoms were gradually aggravated.The symptoms of FACT-cog were correlated with TCM symptoms after chemotherapy.After 3 months of follow-up，TCM symptom scores in the observation group were lower than those in the control group(P<0.05).Conclusion:Although the effect of Sanyin Formula on the improvement of cognitive ability after chemotherapy remains unclear，this formula can alleviate the self-perceived symptoms of cognitive impairment in TNBC patients by relieving discomfort symptoms related to chemotherapy and may exert a preventive effect on the cognitive decline related to chemotherapy.