<p>Underground grain squat silos offer a series of advantages, including energy saving, low carbon emissions, and environmental protection, which are of great significance in the context of food security. To investigate the behavior of particle dynamics and the dynamic response between the silo and particles in the underground grain squat silo during eccentric discharge, a combination of numerical simulation and theoretical analysis was employed. A mathematical model was constructed using the discrete element method, and a comparison with Janssen’s theory corroborated its validity. The particle dynamics behavior of eccentric discharge was examined through the established numerical model, with a view to elucidating the variations in dynamic pressure, particle contact stress, velocity, and angular velocity that occur under eccentric discharge conditions. The results demonstrate that: (1) The dynamic pressure and overpressure coefficients exhibit variation in different directions during eccentric discharge, with a gradual decrease observed with increasing discharge hole. (2) The incorporation of a central cylinder introduces a more intricate flow path for the particles during the discharge process. As the number of discharge hole increases, the flow path of the particles extends in length, and the velocity of the particles gradually increases, while the angular velocity and contact stress gradually decrease. (3) The displacement of the silo is relatively minor and diminishes as the quantity of discharge apertures rises. This paper offers a theoretical reference for the optimization of the structural design, grain discharge process, and overall performance of underground grain squat silos.</p> Graphical abstract <p></p>