High cutting slopes with nearly horizontal soft-hard alternant strata are widely distributed in three gorges reservoir area, the soft and hard rocks are mainly mud stone and sandstone of Jurassic system. Sliding failure of this kind of slope is also the main geo-hazards in this area. Firstly, this paper analyzed the impact of topography, water as well as the differential weathering and combination characteristics of soft and hard rocks etc. on the sliding failure of slopes; secondly, sliding failure modes of this kind of slope were classified into four types including circular sliding, sliding along the extroversion structural surface, sliding along the mudded intercalation and wedge sliding, they were analyzed combined with case study. And lastly, support methods against the certain failure mode were put forward. The research results are significant to the support and treatment of high cutting slopes in Three gorges area.