Abstract: The movement path, impact force magnitude, and arrival probability of falling rocks in seismic collapse are influenced by many factors and have significant uncertainty characteristics. Among these factors, slope surface morphology is one of the most important uncertainty factors affecting collapse movement. In this study, the fractal geometry method and uncertainty theory were used to simulate the slope surface fractal characteristics at the entrance of Lehong Tunnel in Yunnan Province. After that, five influencing factors—slope fractal dimension, slope surface cover, rock quality, seismic intensity, and initial height of rockfall—were selected to simulate rockfall movement in Rocfall software based on the principle of orthogonal testing. The results show that the fractal Brownian motion model method can successfully simulate the fractal characteristics of the slope surface; the fractal dimension of the slope surface, slope surface cover, and seismic intensity significantly impact the horizontal movement distance and maximum bounce height of falling rocks; the slope surface cover and the weight of falling rocks have a considerable impact on the maximum kinetic energy of falling rocks; the probability of falling rocks reaching the tunnel entrance and the impact kinetic energy are significantly influenced by the slope surface cover. It is verified that the model obtained by the multiple linear regression method can better predict rockfall movement in the study area and can easily and quickly estimate the uncertainty range of the characteristic parameters of rockfall movement, providing the necessary reference for the analysis of the risk of rockfall and the design of prevention engineering in the field.