Multi-source　Synthetic　Aperture　Radar　(SAR)　datasets　are　used　to　investigate　the　deformation　history　and　failure　mechanism　of　small-scale　loess　landslide　in　the　Heifangtai　loess　terrace,　Gansu　province,　China.　A　total　of　65　SAR　datasets　acquired　by　L-band　ascending　ALOS/PALSAR,　X-band　descending　TerraSAR-X　and　C-band　descending　Sentinel-1A/B　covering　the　different　periods　of　Heifangtai　terrace　are　fully　exploited.　In　addition,　groundwater　level　data　are　also　involved　to　analyze　the　failure　mechanism　of　loess　landslide.　The　displacements　occurred　during　the　past　eleven　years　were　quantitatively　identified　for　firstly　by　InSAR　technique.　The　results　show　that　three　slopes,　failed　on　October　1,　2017　had　large　cumulative　deformations　from　January　2016　to　November　2016.　The　acceleration　dates　of　the　deformation　for　the　three　slopes　were　successfully　captured　by　Sentinel-1A/B　data.　Furthermore,　the　result　shows　that　the　magnitude　of　the　landslide　deformation　is　closely　correlated　to　the　groundwater　level　variation.