Dynamic　model　of　the　moving　belt　system　with　tensioner　pulley　is　studied　in　this　paper.　Belt　is　considered　elastic　continuous　element,　and　pulley　and　tensioner　arm　are　discrete　element.　Considering　the　geometrical　nonlinearity　and　Kelvin　viscoelastic　constitutive　model,　the　kinetic　energy,　potential　energy　and　work　done　by　external　forces　of　moving　belt　system　with　tensioner　pulley　are　given　respectively.　Then,　the　nonlinear　equations　of　motion　for　the　moving　viscoelastic　belt　system　with　tensioner　pulley　are　obtained　by　using　the　Hamilton＇s　principle.　Note　that　nonlinear　oscillations　of　the　belt　and　pulley　oscillations　are　coupled.