Using TNBC cell lines, it was confirmed that METTL3 could inhibit metastasis by increasing the level of m6A modification, and COL3A1 was identified as one of the possible target genes of METTL3. Furthermore, reduced expression of METTL3 was proved to be able to contributes the potential of mobility of triple-negative breast cancer cells by m6A methylation-mediated COL3A1 up-regulation. Here, METTL3 is linked to triple-negative breast carcinoma.