Abstract: Vertical silo is a kind of cylindrical structure for the storage of all kinds of bulk materials, which is widely used in various industries, especially in the grain industry. It has many advantages, such as small area, large warehouse capacity, high labor productivity, and can meet the needs of transit and storage. The dynamic lateral pressure of grain vertical silo during unloading is an important factor to be considered in the design of silo body, and the value of dynamic lateral pressure is directly related to the safety of vertical silo during unloading. In order to study the dynamic lateral pressure distribution and overpressure coefficient of vertical silo during stratified unloading, one-time unloading and layered unloading tests of vertical silo model were carried out respectively.The dynamic lateral pressure at different heights of the vertical silo model under two different unloading conditions was measured, and the dynamic lateral pressure distribution and the corresponding overpressure coefficient were compared and analyzed.The results showed that the static lateral pressure distribution of the full silo was larger than that calculated by the standard formula, and the maximum static lateral pressure appeared at the connection between the silo wall and the funnel; during the layered unloading, the static lateral pressure at the funnel after stable unloading was 3% higher than that of the previous unloading, which should be paid more attention in the structural design; during one-time unloading, the overpressure coefficient in the 2/3h_n range of the lower part of the silo was obviously different at different discharge velocities. The overpressure coefficients with the depth of 0.5 m, 0.8 m and 1.1 m along the measuring point were increased by 10.8%, 1.9% and 0.7% respectively compared with the slow relatively flow velocities; during one-time unloading, the overpressure coefficient was the highest in the 1/3h_n range of the lower part of the silo; during layered unloading, the overpressure coefficient in the 1/3h_n range of the lower part of the silo was higher than that of one-time unloading, and the horizontal lateral pressure correction coefficient C_h=2.0 of the current code was unsafe. The research results revealed the difference law of dynamic lateral pressure distribution during stratified unloading, clarify the influence of stratified unloading on the dynamic lateral pressure of silo, and further compensated the deficiency in the study of dynamic lateral pressure during stratified unloading,providing an experimental support and a theoretical basis for vertical silo structure design.