In southwestern of China

the stability problem of the complex high slopes subjected to excavation has become one of the key technical problems in the hydropower project construction. Based on the geomorphic conditions

characteristics of geologic framework and stress measurement data of the left bank slope of Baihetan hydropower station

by using the discrete element analysis procedure UDEC

a calculation model was established to study the stability of the left bank slope during excavation unloading. The principal stress field

deformation field and plastic yielded zones distribution law were studied under the condition of excavation

then the deformation mechanism of the left bank bedding rock slope has been declared. Meanwhile

the potential damage zone and critical sliding surface in deep rock mass were identified and delineated

by combination with the microseismic activity at the left bank slope during the periods of excavation and stress redistribution. The comprehensive studies indicated that the deformation of the left bank slope is mainly affected by multiple factors

such as tectonic stress

geological structure and unloading. The weak structure planes

such as LS3318

LS3319

LS331

LS337 and F17

play a decisive role in the excavation deformation of the left bank slope. The research results can provide valuable references for excavation and reinforcement of similar bedding rock slope projects.