Abstract: Siltized intercalation is a typical weak structural plane, which often induces all kinds of engineering geological problems, such as slope instability, dam foundation instability and surrounding rock deformations of underground caverns. Therefore, studying the geological characteristics and the evolution progress of siltized intercalation and finding out the influence of siltized intercalation on slope stability is of great importance. This paper reviewed the formation mechanism, classification, spatial distribution, mechanical properties, geological characteristics and sliding stability of siltized intercalation in China. In general, the following main conclusions are obtained. There are three kinds of formation modes of siltized intercalation and interlayer dislocation is the most common formation model. The study of the spatial distribution of siltized intercalation mainly focuses on qualitative description and regular summary. Siltized intercalation is a visco-elastic-plastic system, the shear creep properties of siltized intercalation well studied. Finally, this paper also puts forward the key directions of the studies about the issues. They include the argilization process of weak interlayer, the three-dimensional spatial distribution and visualization of the siltized intercalation, shear creep theoretical model for siltized intercalation, the meso-damage and failure process, stress relaxation properties and the dynamic properties of siltized intercalation, the mechanical properties of composite rock mass and the interface between siltized intercalation and surrounding rock, the extensive and in-depth exploration of the effects of siltized intercalation on slope stability.