Subsea　tunnel　construction　has　become　the　prevalent　tendency　connecting　countries　and　districts,　Controlling　and　minimizing　the　negative　influence　of　channel　dredging　on　tunnel　have　great　significance　throughout　the　tunnel　construction　and　operation　phase.　So　a　three-dimensional　finite　element　model　of　soil-tunnel　and　port　structures　was　established　given　the　tunnel　surrounding　rock　to　be　isotropic　elasto-plastic　media　meeting　Drucker-Prager　criterion　of　continuum,　the　construction　conditions　of　channel　excavation,　back　silting　and　desilting　were　investigated　and　the　calculation　results　were　analyzed.　The　numerical　calculation　results　show　that:　the　channel　dredging　increased　the　deformation　and　stress　discrepancy　along　the　tunnel　longitudinal　direction,　the　distinct　affection　happened　at　the　locations　beneath　the　ocean　bottom,　and　the　maximum　value　occurred　mainly　at　the　position　of　tunnel　segments　in　the　domain　of　retaining　wall.　Moreover,　channel　dredging　decreased　the　ground　settlement　induced　by　tunnel　excavation,　and　siltation　made　partially　the　spring-back　displacement.　Therefore　an　evaluation　of　the　influence　of　repeated　loads　on　tunnel　should　also　be　considered　integrally　to　determine　the　dredging　scheme　in　the　future　project.