Abstract: In this paper,It is firstly used of evolving factor analysis（EFA） into analyzing AES depth profiles of Ta₂O₅/Ta sample.It found three different chemical states of tantalum which were Ta,Ta₂O₅and TaO _x, and discovered that,the film would decompose and produce unstable TaO_x component when Ta₂O₅ film was being sputtered by Ar ⁺ ion. x value was 1.6 and atomic concentration was about to 40%,but no tantalum emerged in Ta₂O₅ during profiling.