Abstract: The new landslide at K52 Luyang freeway is a new-reactivated landslide, which is in the accumulation of the giant landslides formed in ancient time. This landslide is in a state of rapid deformation, which requires the emergent treatment immediately. Many steps including geological survey, drilling, in-situ test, laboratory test, and deformation monitoring are applied to analysis this giant landslide after the resumption of construction, where the characteristics of geomorphology, stratum structure, sliding surface, sliding mass, sliding bed, deformation, and hydrogeology of the landslide were identified. By using FLAC^3D software, several aspects containing the cause of this sliding and deformation mechanism were analyzed, The following conclusions were given after the functional investigation: (1) The giant ancient landslide accumulation was formed by deep rock landslide. Soft plastic weak intercalated weathered shale is developed in the accumulation body, which is the main sliding zone soil of the new landslide; (2) The main internal causes of the new landslide were unfavorable geology, micro landform, and the special geotechnical structure, while the main external causes were artificial loading on the middle and back part of the accumulation of the ancient landslide and rainfall; (3) There were three sliding surfaces, the lowest surface was the main sliding surface at the creep stage, the mddle surface was the main sliding surface at the unstable stage, and this sliding could be classified as the composite sliding of pushing from the front section and dragging by the back section, which had the features of multiply-stage, progressively gradual failure; (4) The deformation process of this new landslide was: firstly, there was a tensile deformation in the back part of the initial landslide and a shear creep in the middle. Then, the sliding A and B lost stability due to shear failure in the front edge, and the sliding C failed caused by the tensile force due to the lost support in the front edge; (5) The key point of new landslide treatment is to prevent the deformation of the top, mddle and lowest sliding surfaces, and to prevent the secondary sliding of the ancient sliding surface and other weathered shale Intercalations in the ancient landslide accumulation, which may be used as an acceptable reference for the uses of research and design by the similar engineering fields.