Hydrogen isotopes permeation barriers (HIPB) play an important role in reducing hydrogen isotopes permeation and leakage in hydrogen energy and thermonuclear fusion energy. In this study, the Al2O3-HIPB were prepared on 316L stainless steel by RF magnetron sputtering. The impacts of coating thickness and annealing temperature of as-deposited coatings on deuterium permeation reduction factor (D-PRF) are studied in detail. With increasing thickness of coatings from 0.2 mu m to 1.6 mu m, the D-PRF did not rise significantly, which indicated that coating surface, for thin coatings, played more important role in impeding deuterium permeation than coating interior. As a result of further crystallization and grain growth, the 700 degrees C-annealed Al2O3 coatings had stronger ability to impede deuterium permeation than 600 degrees C-annealed Al2O3 coatings. This further proofs that grain boundaries may be a short-cut path for deuterium diffusion in Al2O3 coatings. The D-PRF drastically decreased when the annealing temperature reaches 800 degrees C, which might be ascribed to the new phases form and the coating cracks appearance after 800 degrees C annealing. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.