Inclusion Criteria:  Age: 18-70 years old Women with known menstrual status (at the beginning of randomization or adjuvant endocrine therapy). Postmenopausal status is defined as (1) The patient has undergone bilateral ovariectomy, or (2) Age ≥ 60 years, or age < 60 years, amenorrhea for 12 months or more (without chemotherapy, tamoxifen, toremifene or ovarian suppression), and follicle stimulating hormone (FSH) and plasma estradiol are within the normal range of local postmenopausal women.(3) If the patient is taking tamoxifen or toremifene and is younger than 60 years old, the FSH and plasma estradiol levels are within the postmenopausal range (Notes:For premenopausal women before the start of adjuvant chemotherapy, amenorrhea is not a reliable indicator of menopausal status. Ovarian function may be complete or restored despite anovulation/amenorrhea. For women with treatment-induced amenorrhea, continuous measurements of FSH and/or estradiol are required according to clinical guidelines to determine postmenopausal status.) Invasive breast cancer patients with HR (+) and HER2(-), which is confirmed by histopathology. (1) ER and/or PR positive (positive staining accounted for more than 1% of all tumor cells) (2) HER-2 negative (IHC 0, 1+, or IHC 2 + and no fish amplification) Patients received radical surgery and chemotherapy (neoadjuvant or adjuvant chemotherapy), and for patients who received neoadjuvant chemotherapy, at least one of the following conditions should be met: (1) Patients not achieving PCR after neoadjuvant chemotherapy; (2) Axillary lymph nodes metastasis (including micro-metastasis) were confirmed by cytology or histology before neoadjuvant chemotherapy. Patients who have received breast cancer treatment in the past should meet the following conditions at the same time: (1) No more than 1 year after radical mastectomy. (2) For the patients receiving adjuvant chemotherapy, the time from the last chemotherapy to the beginning of enrollment should be more than 21 days. (3) For patients receiving radiotherapy, it should be no less than 14 days from the date of last radiotherapy to the beginning of enrollment. (4) Endocrine therapy should not exceed 6 months before entering the study (calculated as 30 days per month); The following laboratory results should be met to determine that the patient has sufficient bone marrow and organ function: Absolute neutrophil count (ANC) ≥ 1.5 × 109/L; Platelet ≥ 100 × 109/L; hemoglobin ≥ 9.0 g / dl; Creatinine clearance rate ≥ 50ml/min; alanine aminotransferase (ALT)< 2.5 × Upper limit of normal range (ULN); aspartate aminotransferase (AST) < 2.5 × ULN. For patients receiving anthracycline chemotherapy, EF value of cardiac ultrasound was ≥ 55% within 14 days before randomization; If the patient is a woman of childbearing age, the serum pregnancy test was negative within 14 days before randomization. ECOG score was 0 or 1. Patient has signed informed consent voluntarily.  Exclusion Criteria:  Double primary cancers in active stage (simultaneous double primary cancers and heterochronous double primary cancers with disease-free interval ≤ 5 years). Note: carcinoma in situ (intraepithelial carcinoma or lesion equivalent to mucosal carcinoma) cured by local treatment is not included in active double primary carcinoma. Bilateral breast cancer (simultaneous/metachronous) (Notes: patients with invasive breast cancer combined with contralateral DCIS, the patient was considered eligible for inclusion if the contralateral DCIS have been removed with radical surgery) Received oral 5-FU for more than 2 weeks before treatment (Notes: patient with a history of intravenous 5-FU was considered eligible for inclusion). Severe Diarrhea. Combined with the following serious complications: (1) Uncontrolled diabetes; (2) Uncontrolled hypertension; (3) Unstable angina and arrhythmias need treatment; (4) cirrhosis and liver failure (5) Interstitial pneumonia, pulmonary fibrosis and severe emphysema; (6) Active infection; (7) Other serious complications. Past medical history: (1) myocardial infarction within 6 months; (2) Interstitial pneumonia (For local interstitial pneumonia, it can be proved to improve after treatment. Not included in this definition). (3) History of fluorouracil allergy; (4) Pregnant and lactating women; (5) Other patients not suitable for inclusion.