Axillary lymph node metastasis (ALNM) in triple negative breast cancer (TNBC) will lead to poor prognosis. Recent studies have shown that long non-coding RNAs (lncRNAs) were involved in the progression of tumors. This study aimed to explore the role and mechanism of lncRNA-MALAT1 in the progression of TNBC and its relationship with ALNM. MALAT1 is highly expressed in TNBC cells lines, tumor tissues and serum, and it is positively correlated with the degree of ALNM. In addition, MALAT1 can act as a competitive endogenous RNA (ceRNA) that regulates cellular biological behavior by competitively binding to miR-106a-5p with REEP5. In conclusion, our results show that MALAT1 could function as ceRNA promote the proliferation, invasion and metastasis of TNBC cells through MALAT1/miR-106a-5p/REEP5 axis, which is expected to provide new ideas for the diagnosis of TNBC in clinic.