Objective To investigate the expression of microRNA-134 (miR-134) in female breast carcinoma and its role for tumor cell migration and invasion. Methods Between January 2013 and February 2015, 30 ductal carcinoma in situ (DCIS) tissues, 35 invasive breast ductal carcinoma (IBDC) tissues and 15 normal breast tissues were collected and investigated. The expressions of miR-134 were detected by qRT-PCR. The relationship between miR-134 and clinical features was analyzed by student-t test. miR-134 mimics was transfected into MDA-MB-231 cells. Wound healing assay and transwell assay were used to measure cell migration and invasion, respectively. The correlation between miR-134 and forkhead box protein M1, a potential target of miR-134, was analyzed by IHC staining. The expression changes of M1 and downstream effector molecules of human MMP2 in the potential target of  the downstream potential target after microRNA-134 mimics infection were detected by qRT-PCR and western blotting. Results The expression of MiR-134 was significantly gradually decreased from normal breast tissue, in situ breast ductal carcinoma and invasive ductal carcinoma of the breast. The low expression of MiR-134 in breast cancer was significantly correlated with tumor lymph node metastasis and TNM stage (P < 0.05). The migration and invasion of MDA-MB-231 cells capability were significantly reduced by over expression of MiR-134 in vitro. The expression of miR-134 and the fork head box M1 was negative correlation confirmed by IHC (P < 0.05). The results of qRT-PCR and western blotting showed over expression of MiR-134 could suppress breast cancer cells forkhead box protein M1 and MMP2 expression level (P < 0.05). Conclusions MiR-134 expression is down regulated in breast cancer tissues. miR-134 may inhibit the migration and invasion of breast cancer cells by down regulating the expression of M1/MMP2 2.