According　to　the　nonlinear　creep　properties　of　earth-rock　aggregate　embankment　after　construction,　a　modified　Kelvin　model　that　can　express　nonlinear　viscoelastic　deformation　of　material　is　presented.　Based　on　the　current　research　results　of　the　creep　mechanism　of　earth-rock　aggregate　embankment,　the　creep　settlement　after　construction　is　considered　to　be　an　attenuation　creep　process;　and　the　modified　Kelvin　model,　generalized　modified　model　and　recognition　method　of　model　parameters　are　presented.　Through　analyzing　the　modified　Kelvin　model,　the　results　show　that:　the　nonlinear　constant　is　an　important　influencing　factor　to　the　model;　and　long-term　strain　of　the　modified　Kelvin　model　is　smaller　than　that　of　Kelvin　model.　Based　on　the　creep　test　data　in　the　related　literatures,　parameters　of　modified　Kelvin　model　are　fitted;　and　the　fitting　effect　is　well.　The　modified　Kelvin　model　will　distribute　theoretical　basis　for　the　numerical　calculation　program　of　nonlinear　viscoelasticity.