Geological hazards occur frequently in the southwest mountainous area. In recent years, successive large-scale landslide hazards such as Maoxian landslide, Baige landslide, and Shuicheng landslide have shown that the occurrence of catastrophic landslide events is not only related to the conditions that are prone to breeding geological hazards in the area, and failure to accurately identify and monitor the development of landslide disasters is also a major factors. Located in the "Sanjiang" area on the southeastern edge of the Qinghai-Tibet Plateau, the terrain is high and steep with frequent geological disasters. The condition of Lantsang watershed is more severe, with high altitude and steep terrain. The mountains and forests are dense in summer and autumn and there is a lot of rainfall. It is cold and snowy in spring and winter. However, the traditional ground-based geological hazard survey methods have limited effects here, and optical remote sensing technology is also subject to many limitations of weather conditions. InSAR technology based on active microwave remote sensing imaging has proven to be suitable for the identification of geological hazards in areas not easily reached by humans. In this paper, a segment of Meri Snow Mountain in the Lantsang Basin is used as the study area, and multi-source radar remote sensing data, such as PALSAR1, PALSAR2, and Sentinel-1 data, are used in combination with D-InSAR and IPTA-InSAR technologies to carry out accurate identification of landslide disasters in steep valleys of glacial dense forests. It was found that the long-wavelength PALSAR1 and PALSAR2 data have better adaptability. The short-wavelength Sentinel-1 data makes up for the shortcomings of insufficient penetration energy by virtue of the large amount of data. It successfully interpreted 92 active landslides in the study area, there are 26 sites with a plane area of ??more than 20×104m2; the results of time series InSAR technology combined with ground survey verification show that the typical large landslides in the Lantsang Valley, such as the Meili water landslide and the Yagong landslide have a high activity rate and high danger. As typical landslides around Deqin County area, the Dingyangding landslide and Guibading landslide are in the creep state as a whole, and the local deformation rate is high. At the same time, debris flow and moraine movement around Deqin County are more active.
