Trust　estimation　plays　an　important　role　in　research　of　Trusted　Computing.　However,　the　method　for　trust　estimation　often　has　the　property　of　oneness　for　the　moment.　In　this　paper,　the　degree　of　trust　of　a　component　is　extended　to　a　vector.　To　estimate　the　trust　of　a　component,　the　relation　of　dependency　between　components　is　studied　thoroughly,　followed　by　the　concepts　of　the　path　and　path　set.　Using　the　above,　a　layered　structure　is　presented　and　finally,　the　method　for　trust　estimation　is　proposed.