Damage　detection　indexes　have　their　own　characteristic　and　deficiency.　Strain　mode　is　sensitive　to　structure　local　characteristic　changes　and　has　a　great　theory　foundation.　But　effect　of　only　using　strain　mode　index　is　not　ideal.　As　the　reaction　of　structure　integral　property,　structure　damage　identification　index　based　on　frequency　can＇t　realize　exact　locations　of　damage,　though　it　can　be　measured　conveniently　with　high　precision　and　widely　used　in　engineering.　In　order　to　locate　precisely　and　be　applied　in　engineering,　a　new　practical　combination　index　based　strain　mode　and　frequency　is　presented.　Theory　analysis　and　mathematical　simulation　indicate　those　combination　indexes　of　low-order　and　high-order　mode　can　identify　damage　existence　and　locate　exactly　for　a　single　crack　and　multi-cracks.