Angiotensin II (AngII) is involved in the pathogenesis of hypertensive artery remodeling by inducing a phenotypic switch in vascular smooth muscle cells [Gly14]-Humanin (HNG), a humanin analogue, exerts potent cytoprotective effects both in vitro and in vivo. This study aimed to investigate the effects of HNG on an AngII-induced phenotypic switch in VSMCs and the potential mechanisms underlying these effects. The roles of [Gly14]-Humanin in AngII-stimulated VSMCs proliferation and migration was detected by CCK-8 assay, Cell cycle analysis, wound healing assay, trsnswell assay and western blot. The mechanism by which [Gly14]-Humanin regulates VSMC phenotypic switch was determined by intracellular oxidative stress detection, transcriptomic analysis and qRT-PCR. The results showed that HNG inhibited AngII-induced VSMC proliferation and migration and maintained a stable VSMC contractile phenotype. In addition, HNG reduced the level of AngII-induced oxidative stress in vascular smooth muscle cells. This process could be accomplished by inhibiting nicotinamide adenine dinucleotide phosphate oxidase activity. In conclusion, the results suggested that HNG ameliorated intracellular oxidative stress by inhibiting NAD(P)H oxidase activity, thereby suppressing the AngII-induced VSMC phenotype switch. Thus, HNG is a potential drug to ameliorate artery remodeling in hypertension.