Abstract:   Objectives:   The response law of ancient (old) landslides in the reservoir area with changes in reservoir water level is an important research topic. Previous studies have mostly used surface displacement real-time monitoring data coupled with reservoir water level data for analysis. However, most reservoir bank slopes do not have the conditions for professional monitoring. This brings certain difficulties to the tracing of the historical deformation of the landslide.   Methods:   This paper uses the air, space and ground multi-source three-dimensional observation technology to monitor the deformation and evolution of the Pubugou Hydropower Station Hongyanzi landslide from water storage to about 10 years from the impoundment to the present, and use UAV aerial photography (optical imaging) technology to find out in 2009 from multiple angles and scales.~2020 A total of 6 periods of Hongyanzi landslide macroscopic deformation and failure characteristics, airborne LiDAR carried out two periods of landslide topography mapping in 2009 and 2020, and calculated topographic differences to calculate the landslide elevation changes for more than 10 years, and timeseries InSAR technology to monitor landslides Long-term series of surface deformation from October 2014 to July 2020. Field investigation and investigation techniques have identified the typical deformation and failure characteristics of landslides at this stage, and combined the landslide's own geological conditions and external environmental factors (rainfall, reservoir water level, etc.) Analyze the cause mechanism and dynamic evolution trend.   Results:   The Hongyanzi landslide has an irregular semicircular shape in plan, with a thickness of 20-50m, a volume of about 15.53 million m3, and a sliding direction of about 340°. The landslide is composed of quaternary crushed (pebbled) stones and silty sand. It is composed of clay, the slope of the slide bed is 20°~25°, and the lithology is basalt of Emeishan Formation and dolomite of Yangxin Formation. The landslide already had various elements such as landslide wall and landslide steps in 2006 or even earlier. In 2009, LiDAR images showed that the landslide boundary was obvious, but there were no obvious signs of fresh deformation and failure. After the reservoir was impounded, the landslide was revived, and obvious fresh cracks appeared on the rear edge of the landslide, and they continued to be pulled apart. After the resurrection of the landslide, the main deformation is the overall deformation. The deformation of the trailing edge is larger than that of the leading edge. It is always in the stage of uniform deformation without significant acceleration deformation. It is most obviously controlled by heavy rainfall, showing certain step deformation characteristics.   Conclusions:   A comprehensive study of multi-source data shows that water storage and rainfall-induced creep-pulling landslides such as Hongyanzi landslide have typical long-term, slow and seasonal characteristics, and long-term InSAR can accurately capture these landslides. Feature information, multi-stage optical remote sensing image comparison and analysis can more intuitively show the differences in macroscopic deformation and failure characteristics of landslides at different locations, and the surface point cloud information obtained by airborne LiDAR can accurately identify long-term creep after vegetation removal. Changes in landslide elements, on the basis of the above work, combined with geological conditions and surface landslide investigations, carry out engineering geological analysis, and finally determine the genesis mechanism, deformation mode and future development trend of landslides.