• The subjects voluntarily joins the study and signs the informed consent;

• Subject is an adult female or male ≥ 18 years old and ≤ 75 years old at the time of informed consent;

• HER2-positive advanced breast cancer confirmed by pathology:HER2-positive was defined as \>10% of immunoreactive cells with an immunohistochemical (IHC) score of 3+ or HER2 gene amplification as a result of in situ hybridization (ISH). HER2 positivity should be verified by the pathology department of the research center;

• Recurrent or metastatic breast cancer; Patients with local recurrence had to be confirmed by the investigator as not amenable to curative resection;

• At least one measurable lesion or only bone metastases according to RECIST v1.1 criteria (including osteolytic lesions or mixed osteolytic/osteoblastic lesions);

• When randomized, Eastern Cooperative Oncology Group(ECGO) physical fitness status is 0 or 1 point;

• Vital organ function meets the following requirements (excluding the use of any blood components and cell growth factors during screening) : Absolute neutrophil (ANC) count ≥1.5×109/L; Platelet (PLT) ≥100×109/L; Hemoglobin (HB) ≥9g/dL; Total Bilirubin(TBIL) ≤ULN((Known patients with Gilbert's syndrome:Total Bilirubin(TBIL) ≤2×ULN);Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤1.5×ULN(Patients with liver metastasis:ALT and AST≤5×ULN); Alkaline phosphatase (AKP) ≤ 2.5 times ULN; Blood Urea Nitrogen and Serum creatinine (Cr) ≤1.5×ULN;Left Ventricular Ejection Fractions(LVEF)≥50%;Corrected QT Interval(QTcF)\<470msec.