Abstract: Excavation activity is one of the most active factors to cause the loess geo-hazards. In order to reveal the deformation and failure characteristics of the excavated loess slope under unloading, exfoliation and erosion, and its influence on the slope stability, 23 excavated loess slopes have been studied through carrying out field investigation, in-situ micro penetration test and indoor test in Yan'an area, Shaanxi Province. The results show that there is a linear positive correlation between the thickness of slope unloading exfoliation layer and the slope excavation age, and there is a negatively power correlation between the on-site penetration resistance value and the slope excavation age, and the shallow soil chemical erosion is stronger than deep soil. The deformation and failure modes of excavated loess slopes are mainly slip-type collapse and creep-slipping shallow landslide. The failure and evolution process of collapse is mainly "exfoliation erosion-concave-crack-slip", while the failure and evolution process of landslide is mainly "creep-pull-through-slip".