This chapter presents a comprehensive study on the microseismic monitoring and stability analysis of highly steep rock slopes, with a focus on the right bank slope of the Dagangshan Hydropower Station. It begins by highlighting the research background and significance, followed by a review of domestic and international studies on excavation disturbances, numerical simulations, microseismic monitoring, and reinforcement effects, thereby identifying key challenges as the basis of the chapter. The engineering geological conditions of the right bank slope are then analyzed, and two- and three-dimensional numerical simulations are employed to assess slope stability. Subsequently, the construction and application of a microseismic monitoring system are described, revealing the spatiotemporal distribution of disturbances, the evolution of microseismic energy density, and the primary structural planes influencing slope stability, as well as investigating the causes of fractures during excavation and unloading. Finally, the reinforcement effect of anti-shear galleries is evaluated through microseismic data analysis and RFPA2D-SRM modeling, focusing on energy distribution, stability, and reinforcement performance. By integrating numerical simulations with microseismic monitoring, the chapter offers valuable insights into slope stability and reinforcement strategies, thereby supporting the optimization of engineering practices.