<p>Rapid Drawdown may have a significant impact on the stability of the upstream slope of earthen dams. To avoid potential hazards, it is important to calculate the slope safety factor changes during the Rapid Drawdown process. However, considering the resistance parameters of the dam body definitively and ignoring the existing uncertainties does not lead to an accurate analysis of the slope stability conditions. Embracing the probabilistic characteristics of soil properties, instead of depending exclusively on fixed deterministic values, offers a more precise portrayal of the system’s performance and supports better-informed engineering choices. Moreover, the stability of earth dams remains a vital issue, given that their failure could result in severe and lasting impacts. This study aims to provide a comprehensive understanding of the probabilistic stability of earth dams, focusing on Rapid drawdown conditions. Seydon Dam in Iran was analyzed using the slide Rocscience software for this research. The results show that the dam discharge time in Rapid Drawdown conditions has a significant impact on the stability and reliability of the upstream slope. On the other hand, the seismic analysis of the dam shows that determining the appropriate dam discharge interval is very important in the stability of the upstream slope of the dam. Also, the results of the spatial variation analysis show the importance of the length correlation on the reliability results of the upstream slope during the Rapid Drawdown process.</p>