Pyrotinib is an oral tyrosine kinase inhibitor targeting both HER-1 and HER-2 receptors. This study is a randomized, multi-center, multinational, open-label, active-controlled, parallel design study of the combination of pyrotinib plus capecitabine versus the combination of lapatinib plus capecitabine in HER2+ MBC patients who have prior received anthracyclin, taxane or trastuzumab. Patients will be stratified by weather have prior use of trastuzumab and randomized in a 1:1 ratio to one of the following treatment arms:

• Arm A: pyrotinib (400 mg once daily) + capecitabine (1000 mg/m^2 twice daily)
• Arm B: lapatinib (1250 mg once daily) + capecitabine (1000 mg/m^2 twice daily) Patients will receive either arm of therapy until the occurrence of death, disease progression, unacceptable toxicity, or other specified withdrawal criterion.

Inclusion Criteria:

• Aged ≥18 and ≤70 years.
• ECOG performance status of 0 to 1.
• Life expectancy of more than 12 weeks.
• At least one measurable lesion exists.(RECIST 1.1).
• Histologically or cytologic confirmed HER2 positive advanced breast cancer which failed prior therapies.
• Required laboratory values including following parameters:

ANC: ≥ 1.5 x 10^9/L;Platelet count: ≥ 100 x 10^9/L;Hemoglobin: ≥ 9.0 g/dL;Total bilirubin: ≤ 1.5 x upper limit of normal (ULN);ALT and AST: ≤ 1.5 x ULN;BUN and creatine clearance rate: ≥ 50 mL/min;LVEF: ≥ 50%;QTcF: < 470 ms for female and < 450 ms for male.

• Signed informed consent

Exclusion Criteria:

• Received previous therapy with lapatinib, neratinib, pyrotinib or any other HER2 directe tyrosine kinase inhibitor.
• Received previous therapy with capecitabine within 3 months.