Abstract: The sudden increase and shock distribution of the dynamic pressure of the storage material on silo wall occure when the silo discharges, the mechanical behavior of the stored materials in the static grain storage state and the discharge process were studied by changing the height-diameter ratio of silo by using indoor model test method and the discrete element method, elucidating the mechanical behavior of stored particulate matter and the essential relationship between the two from the macro-flow state and the mioroscomic particle level. A conical funnel silo was tested in which wheat was stored. The loading height was 4.4 m, the diameter was 1.5 m and the funnel height was 0.7 m. On the basis of experimental verification, six deep and shallow model silos with different height-diameter ratios were established by using discrete element PFC^2D software, and the discharging process of silo was simulated numerically. The static pressure, dynamic pressure and overpressure coefficient were analyzed, reasons for the increase of dynamic pressure on the side wall of the silo were explored from macroscopic flow state and microscopic dynamic arch. The results showed that the tested maximum dynamic pressure of the test occurred at about 1/3 in the lower part of the silo, and the simulated maximum dynamic pressure occurred at about 1/4 in the lower part of the silo. For the silo with the same height, the maximum dynamic pressure showed an overall upward, but nonlinear relationship with the increasing diameter of the silo. Different flow states and different dynamic arch occurrence time were the important factors for different dynamic pressures of deep and shallow silos.