Abstract: Tantalum oxide films were prepared on iron substrates by dynamic ion beam mixing where tantalum was deposited with Ar⁺ beam sputtering,and simultaneously bombarded by O+ beam with an energy of 100 keV and a dose of 2×1017/cm² or bombarded by Ar⁺ beam with an energy of 100 keV and a dose of 8×10¹⁶ /cm² .The prepared samples were investigated by XPS,AES and RBS.The results show that the oxide films fabricated by Ar⁺ beam bombardment are mainly Ta₂O₅.While the films fabricated by O+ beam bombardment consist of tantalum suboxides,and the films with O+ beam bombardment were contaminated by more carbon than those with Ar⁺ beam bombardment.