Analyzing　the　strain　of　arterial　wall　pressed　by　the　pressure　is　the　foundation　to　judge　the　arterial　elasticity,　which　is　an　important　reference　to　estimate　Heart-blood　Vessel　System　Function.　In　this　study,　a　method　is　proposed　to　analyze　the　arterial　wall　strain　using　intravascular　ultrasound　(IVUS)images,　the　method　is　based　on　finite　deformation　power　theory,　with　which　a　modal　is　established　and　arterial　wall　is　divided　by　determinate　number　conjoint　triangles　and　the　strain　of　arterial　wall　is　calculated　by　the　foundation　of　these　triangle　elements.　The　merit　of　this　method　is　that　it　predigests　the　research　objects　and　makes　full　use　of　the　character　of　the　triangle　deformation.　At　the　same　time,　the　main　strain　and　main　direction　of　each　element　testifies　the　modal.