Nanoporous magnesium exhibits outstanding performance in hydrogen absorption and desorption, rendering it a promising candidate for hydrogen storage applications. Nevertheless, there is limited discussion on the preparation method and growth mechanism of nano-porous magnesium.In this paper, a novel nanoporous magnesium material characterized by a feathery morphology was successfully synthesized at 823 K for 2 h under a vacuum pressure of 3 Pa, assisted by ethanol vapor through the physical vapor deposition method. The ethanol vapor was identified as the crucial factor in the synthesis of the feathery nanoporous magnesium. A vacancy-assisted formation mechanism is proposed to elucidate the creation of feathery nanoporous magnesium, whereby the ethanol vapor occupies specific positions within the magnesium vapor, resulting in the formation of nano and submicron pores.