Rainfall-induced landslides are a significant concern, and various methods have been developed to mitigate these events. The location of the water table also plays a crucial role in the stability of slopes subjected to rainfall. This study investigates the impact of water table depth on slope stability, focusing on both unreinforced slopes and those reinforced with anti-slide piles. Finite element analysis, incorporating fully coupled flow-deformation analysis and stability analysis, was employed to examine the variation in the factor of safety and failure patterns under different water table conditions. Results reveal that the factor of safety increases with greater water table depth, indicating improved stability. However, rainfall reduces the factor of safety, with the degree of reduction varying based on water table depth. For unreinforced slopes, the failure pattern typically involves toe failure, which becomes more localized with a shallow water table and extends more broadly with a deeper water table. In contrast, slopes reinforced with anti-slide piles predominantly exhibit base failure, demonstrating the effectiveness of piles in preventing toe failure and stabilizing the lower slope regions. This study highlights the significant influence of water table depth and rainfall on slope stability and the effectualness of anti-slide piles in altering failure mechanisms.