Abstract: To reveal the load transfer and cascading pillar failure (CPF) mechanism of multi-pillar systems under the condition of pillar instability with discontinuity, a physical model of double-pillar system with soft loading condition was established based on the engineering context of the two-step open-stope subsequent filling method. The elastic energy storage and rebound process of roof-floor rockmass were simulated using disc spring group. Compression tests on the double-pillar system were conducted under varying discontinuity inclination (40°–60°)and asperity angles (15°–35°). The effects of discontinuity geometry on the bearing capacity, load transfer, sudden jump displacement, and energy release behavior of the multi-pillar system were systematically analyzed. The results indicate that: Shear instability of the jointed pillar leads to a sudden drop in the system’s bearing capacity, triggering elastic rebound of the roof-floor rockmass, and inducing dynamic load transfer to the adjacent intact pillar. The proposed competition criterion of load transfer-residual bearing capacity ( P_\mathrmtransfer\geq P_\mathrmresidual ) can effectively distinguish between successive failure mode and domino failure mode. The discontinuity inclination exhibits a non-monotonic control over the system response, with all response parameters reaching their minimum values around 50°. The load transfer is as low as 5.94 kN, and the elastic energy release is only 0.88 J. The asperity angle exerts an exponential amplification effect on the system response. When the asperity angle increases from 15° to 35°, the load transfer increases from 2.89 kN to 10.56 kN, and the elastic energy release increases from 0.34 J to 10.78 J, with an increase of 265% and 3071%, respectively. Ultimately, it induces the CPF disaster. The discontinuity geometry controls the elastic energy storage of the system, rebound of roof-floor rockmass, and load transfer behavior by regulating the bearing capacity of the jointed pillar. A CPF mechanism of the double-pillar system is established, characterized by "shear instability triggering-roof and floor rebound propagation-dynamic overload instability". The findings of this study can provide a theoretical basis for the stability evaluation of pillar groups containing discontinuities and the prevention and control of dynamic disasters in underground mines.