• Sign the informed consent form voluntarily and follow the protocol requirements;

• Gender is not limited;

• Age ≥18 years old and ≤75 years old;

• Expected survival time for 3 months or more;

• Patients with histologically and/or cytologically confirmed unresectable locally advanced or metastatic HER2-positive breast cancer;

• Consent to provide archived tumor tissue samples or fresh tissue samples from the primary or metastatic lesions;

• At least one measurable lesion meeting the RECIST v1.1 definition was required;

• Physical condition score ECOG 0 or 1 ;

• The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0;

⁃ No severe cardiac dysfunction, left ventricular ejection fraction ≥50%;

⁃ No blood transfusion, no colony-stimulating factor, and no albumin are allowed within 14 days before the first use of the study drug, and the organ function level must meet the requirements;

⁃ Blood coagulation function: international standardization ratio (INR) 1.5 or less, and the part activated clotting time (APTT) live enzymes acuities were 1.5 x ULN;

⁃ Urinary protein ≤2+ or ≤1000mg/24h;

⁃ Fertile female subjects, or male subjects with fertile partners, must use highly effective contraception from 7 days before the first dose until 7 months after the end of the dose. Female subjects of childbearing potential had to have a negative serum pregnancy test within 7 days before the first dose.