Distinctively directing endothelial cells (ECs) and smooth muscle cells (SMCs), potentially by surface topography cue, is of central importance for enhancing bioefficacy of vascular implants. For the first time, surface gradients with a broad range of nano-micrometer roughness are developed on Mg, a promising next-generation biodegradable metal, to carry out a systematic study on the response of ECs and SMCs. Cell adhesion, spreading, and proliferation are quantified along gradients by high-throughput imaging, illustrating drastic divergence between ECs and SMCs, especially in highly rough regions. The profound role of surface topography overcoming the biochemical cue of released Mg2+ is unraveled at different roughness ranges for ECs and SMCs. Further insights into the underlying regulatory mechanism are gained at subcellular and gene levels. Our work enables highefficient exploration of optimized surface morphology for modulating favored cell selectivity of promoting ECs and suppressing SMCs, providing a potential strategy to achieve rapid endothelialization for Mg.