In order to investigate more effective and thinner protective coatings preparation for uranium laser targets, nano-Al coatings prepared by magnetron sputtering were researched, single-layer of Al and DU, Al/DU/Al “sandwich” film samples were prepared, oxidation resistant of nano-Al coatings Al/DU/Al samples under atmosphere environment was investigated. The surface topography, atomic concentration and atomic concentration’s change, and phase composition of these samples were characterized by SEM, XPS and XRD. The results show: Al coating becomes continuous when its thickness exceeds 10 nm, grain size of Al coatings increase with thickness. 30 nm thick Al protective coating effectively avoids DU layer oxidation, no obvious increase of DU layer’s oxygen content under atmosphere environment was found within 72 hours.