Contrary　to　hard　rocks,　the　plastic　deformation　of　soft　rocks　during　the　initial　creep　stage　occurs　more　obviously.　The　traditional　component　models　can　be　used　to　describe　the　visco-plastic　behavior　of　geomaterials,　but　only　when　the　stress　value　is　beyond　the　yield　point.　This　paper　proposes　the　plastic　deformation　as　a　variable　in　the　disturbance　function,　in　the　framework　of　the　Disturbed　State　Concept,　to　describe　the　evolution　characteristics　of　elasto-plastic　states　during　loading　and　unloading.　In　addition,　the　evolution　of　the　disturbance　equation　with　time　is　further　investigated　and　analyzed　according　to　the　relationship　between　plastic　deformation　and　time.　The　Burgers　model　is　applied　to　the　relative　intact　state;　while　the　Bingham　model　is　employed　to　describe　the　fully　adjusted　state.　The　disturbance　function　is　utilized　to　combine　the　two　states.　Following　this　approach,　the　creep　constitutive　model　for　soft　rocks　is　presented.　Comparison　with　the　creep　test　results　of　argillaceous　shale　indicates　that　the　proposed　disturbance　state　constitutive　model　accurately　captures　the　temporal　evolution　of　the　transformation　process　from　the　relative　intact　state　to　the　fully　adjusted　state.　Furthermore,　the　proposed　model　can　better　handle　both　nonlinearity　and　stage　coordination,　and　provides　a　more　profound　description　of　the　initial,　stable　and　accelerating　creep　stages　of　soft　rock.　©　2017,　Editorial　Department　Chinese　Journal　of　Solid　Mechanics.　All　right　reserved.