Our work identified that the abnormal YTHDF1 in breast cancer cells was driven by the hypoxic microenvironment, which could induce the expression of HIF1α while inhibiting endogenous miR-16-5p, of which the latter could interact with 3′UTR of YTHDF1 mRNA to inhibit YTHDF1 expression. This evidence concerns the gene HIF1A and breast cancer.