An underground silo is essential to green grain storage, due to its low temperature, low land consumption, energy conservation, and environmental protection. A new underground silo was proposed in combination with the prefabricated technology and combined structure technology in the engineering practice. In this study, a finite element model of steel plate-concrete composite silo wall containing stud was established on the ABAQUS software, in order to explore the compressive properties of assembled underground silo using the full-scale axial compression test. A nonlinear finite element model of silo wall specimen was also established, concurrently considering the plastic damage of concrete and the elastoplasticity of steel plate. A simulation was performed on the whole loading process of specimens, thereby to analyze the mechanical properties and working mechanism. Various parameters were determined, such as the steel plate strength, concrete strength, and distance thickness ratio. The results showed that: The finite element simulation was in good agreement with the test. Moreover, the relative difference of axial deformation between the simulated and experimental value was 4.2% at 5 000 kN, indicating an applicable finite element model. The precast block concrete and the joint sealing-up steel plate could bear the load of 79.7%, and 50.9%, respectively, during the elastic stage. The peak load depended mainly on the precast concrete of silo wall and the load transfer of steel plates. There was more load in the sealing-up steel plate at the joint position after reaching the peak load. As such, strengthening the sealing-up steel plate can be used to improve the ductility of the specimen. There was the greatest influence of concrete strength on the initial stiffness and the ultimate bearing capacity of specimens, compared with the strength of steel plate, the distance thickness ratio, and sealing-up steel plate thickness. The regression coefficient of concrete strength, steel plate strength, distance thickness ratio, and sealing-up steel plate thickness to peak load were 0.910, 0.154, -0.005, and 0.301, respectively. The specimens were prone to brittle failure, due to the small strength and thickness of sealing-up steel plate. Two curves of load-deformation model were proposed in combination with the load-deformation curves for the silo wall specimens with the assembled steel plate-concrete composite under the various parameters. Furthermore, the simplified formula was also proposed for the axial peak load of the assembled steel plate-concrete composite silo wall. The relative difference of peak loads obtained by the calculation formula and the finite element method was not more than 9%, indicating high accuracy of calculation. The research findings can provide potential guidance for the engineering design of prefabricated underground silo wall.