Objective To investigate whether fat mass and obesity associated (FTO) protein affects the migration of pulmonary artery smooth muscle cells (PASMCs) in hypoxic mice. Methods Mouse pulmonary artery smooth muscle cells (MPASMCs) was cultured in vitro. The hypoxia model of MPASMCs was established in a three-gas incubator (37℃, 1%O2, 5%CO2). The expression of FTO protein was detected by Western blot. FTO overexpression and knockdown plasmids were transfected into MPASMCs to over-express or inhibit FTO expression. Cell Wound healing assay was used to detect cell migration ability. Results The expression of FTO protein in MPASMCs after hypoxia culture was significantly down-regulated. Scratch test indicated that MPASMCs migration was accelerated after hypoxia culture and was significantly slowed down after FTO was overexpressed in MPASMCs. Knockdown FTO expression in MPASMCs in normoxic state showed a "pro-migration" phenotype similar to hypoxic culture. Conclusions Under hypoxic conditions, the expression of FTO protein is down-regulated in MPASMCs and the cells migration ability is enhanced. FTO may be a key regulator of MPASMCs migration