The　stress-strain　relationship　of　soils　is　closely　related　to　the　stress　path.　Generally,　if　the　loading　stress　paths　of　the　soil　are　enough　close　to　the　same　their　stress-strain　relationship　must　be　basically　the　same.　Sequentially,　an　arbitrary　stress　path　can　be　transform　into　another　almost　similar　stress　path　for　which　the　strain　is　more　easily　to　be　calculated,　so　that　the　constitutive　model　for　such　soils　can　be　established.　On　the　basis　of　this　idea,　a　new　constitutive　model　adaptive　to　the　condition　of　cyclic　loading　is　established.　In　the　model　two　parameters　describing　the　plastic　deformation　laws　under　the　conditions　of　constant　stress　ratio　loading　and　constant　mean　stress　respectively　are　introduced　and　a　new　criterion　of　loading-unloading　is　suggested.　The　comparison　with　experimental　result　shows　that　the　proposed　model　reasonably　reflects　the　deformation　characteristics　of　soils　under　the　condition　of　cyclic　loading　and　is　simple　in　form,　in　which　only　five　parameters　of　soil　property　are　involved.