The stability of a reservoir bank slope is influenced by multiple factors in numerical analysis. Proper selection and determination of rock mass parameters remain critical for practical engineering applications. Traditional limit equilibrium methods do not account for the spatial variability of rock and soil parameters, whereas reliability analysis effectively compensates for this limitation. This study analyzes the bank slope of a hydropower station using the Morgenstern-Price method and Monte Carlo simulation. Slope reliability is evaluated under three conditions: reservoir impoundment, rainfall infiltration, and seismic loading, with relevant stability indices calculated. A comprehensive assessment of slope stability during normal operation is conducted. Results indicate that failure probability and reliability index provide a more comprehensive and accurate evaluation of slope stability than a single safety factor. Reliability analysis divides slope stability into two stages: a decreasing stability phase followed by an increasing stability phase. Slope instability due to rainfall infiltration and seismic action exhibits distinct characteristics of delay and sudden failure.