Abstract：Based on field investigation，indoor test and related studies of Badashan landslide group，the basic characteristics and formation mechanism are elaborated. According to different presupposed working conditions，the stability is calculated and evaluated by adopting limit equilibrium analysis method and numerical simulation. At the same time，landslides H3，H4 and H5，which are closely related with tower ground stability of 750 kV transmission line from Guanting to Lanzhou are mainly considered. The results show that coefficients of integral stability of landslides H3，H4 and H5 are all greater than 1.10，and therefore these landslides are under steady state in natural state. As a result，stabilities of towers No.20，21 and 22 can be satisfied. Under rainstorm state，stability coefficient of landslide H3 is slightly less than 1.05 and therefore it is under metastable state. In addition，landslides H4 and H5 are under stable state. As a result，stabilities of towers No.21，22 except for 20 can be satisfied. Under seismic loading with magnitude VIII，stability coefficients of landslides H3，H4 and H5 are all less than 1.0 and therefore they are unstable. As a result，stabilities of towers No.20，21 and 22 can not be satisfied. What¢s more，sensibility analysis of stability influencing parameters on landslides H3，H4 and H5 is carried out. The analytical result shows that internal friction angle of landslide mass is the most sensitive factor that influences the landslide stability. Finally，relevant engineering strengthening measures are provided based on formation mechanism；and quantitative evaluation results of the landslides group to guarantee safe operation of the transmission line are presented. Therefore，the results are of great significance in practice.
