Abstract: Due to the significant differences in mechanical properties among different rock strata in soft-hard interbedded rock masses, open-pit bench blasting is prone to problems such as excessive fragmentation of soft rock, insufficient breakage of hard rock, and large discreteness in muckpile fragment size, which adversely affect blasting quality and subsequent loading and hauling efficiency. To optimize blasting energy distribution and improve rock fragmentation in soft-hard interbedded rock masses, this study takes the Jilongde open-pit coal mine as the engineering background. A three-borehole fluid-solid coupling numerical model was established using ANSYS/LS-DYNA to comparatively analyze the blasting responses of continuous charging, air-deck charging, and water-deck charging under different deck ratios. Field blasting tests were also conducted to validate the numerical simulation results. The peak effective stress in the soft rock zone, the mean effective stress in the hard rock zone, and the box-counting dimension of the damage section were selected as evaluation indices to systematically reveal the influence of different charging structures on stress transmission, energy distribution, and damage range in soft and hard rock strata. The results show that deck charging can effectively regulate the release process of explosive energy along the borehole direction. As the deck ratio increases, the peak effective stress in the soft rock zone generally decreases, indicating that stress concentration in the soft rock is weakened. The mean effective stress in the hard rock zone first remains relatively stable and then decreases, suggesting that an appropriate deck ratio can maintain the stress level required for hard rock fragmentation, whereas an excessive deck ratio reduces the breakage effect of hard rock. Considering both stress response and damage fractal characteristics, deck ratios of 17.0 % and 18.5 % can effectively balance soft-rock fragmentation control and hard-rock breakage, among which the 17.0 % case exhibits a more favorable box-counting dimension of the damage section and a more reasonable damage distribution. Field test results further indicate that, compared with continuous charging, the 17.0 % deck charging scheme can significantly alleviate excessive pulverization of soft rock and improve muckpile fragment size uniformity. In particular, water-deck charging yields the lowest nonuniformity coefficient and the best overall blasting performance. The findings provide a reference for the optimization of charging structures and refined blasting design in open-pit mines with soft-hard interbedded rock masses.