Based on geological environment where landslide located, the characteristics and forming mechanism of the Shixiakou landside at Jiuzhou, Lanzhou, are researched systematically in terms of regional geological investigation, large scale topographical mapping, measurement of micro physiognomy and failure, geophysical survey, soil microtextures in the slipping zone analysis by Scanning Electron Microscope（SEM）. The results show that this landslide has the characteristics of remarkable classification and partitioning, the key elements of inducing the landslide to be revivable are rainfall, unreasonable false virescence irrigation and the high and steep topography in the landslide region. The stability of state is evaluated by different limit equilibrium methods, combining geological environment, on effects of natural state, or rainfall, or earthquake, or rainfall and earthquake. The resuh can take a theoretic guide rule in treatment of the landslide.