Abstract: Objective To investigate the effect of small interfering RNA of lactate dehydrogenase A (siLDHA) on migration and invasion of epidermal growth factor receptor 2 (ErbB2) over expressing breast cancer cell line SK-BR-3, MDA-MB-453 and its molecular mechanism. Methods SK-BR-3 and MDA-MB-453 cells were transfected with siLDHA to interfere with the expression of LDHA. The transfection of scramble siRNA was used as negative control. The LDHA protein levels were detected by Western blot ( P<0.01). Cell migration and invasion was detected by Transwell assays. Lactate dehydrogenase （LDH） activity was measured by LDH assay kit. The glucose and lactate concentration in the culture media was determined by glucose and lactate assay kit, respectively, and then glucose uptake and lactate production by the cells were calculated. Results siLDHA downregulated LDHA protein levels in SK-BR-3 and MDA-MB-453 cells ( P<0.01). Compared with negative control group, siLDHA significantly decreased migration and invasion of SK-BR-3 and MDA-MB-453 cells ( P<0.001). siLDHA reduced LDH activity in SK-BR-3 cells, glucose uptake and lactate production in SK-BR-3 and MDA-MB-453 cells, the difference was significant ( P<0.05). Conclusion Knockdown of LDHA by siRNA inhibits the migration and invasion via downregulation of glycolysis in ErbB2 over expressing breast cancer cell line.