Abstract: The underground silo is of great significance for green grain storage, owing to its advantages of low-temperature grain storage, low land consumption, energy conservation, and environmental protection. In this study, based on the equivalence principle, the vertical straight joint and the circular tenon joint of the prefabricated silo wall were designed. Combined with full scale tests of bending and compressive resistance of silo wall joints, the finite element models of assembled steel plate-concrete composite silo wall and jointless steel plate-concrete composite silo wall were established, and the calculation results of the two models under the most unfavorable conditions were compared and analyzed. The results showed that the stress and deformation capacity of prefabricated and jointless silo walls were similar, and the maximum radial deflection of fabricated silo wall was 3.16 mm, while the maximum radial deflection of jointless silo walls was 3.32 mm, with a relative error of 4.82%. The design approach based on equivalent principle for prefabricated steel plate-concrete composite silo wall was applicable to the whole structure. Therefore, based on the cylindrical shell theory, a simplified formula for calculating the displacements and internal forces of the jointless steel plate-concrete composite silo wall was obtained, and the calculated displacements and internal forces were equivalent to the assembled silo wall. The relative difference between the maximum radial displacement of the assembled silo wall obtained by the finite element method and that obtained by the theoretical solution was 12%, and the relative difference between the maximum circumferential axial force of the assembled silo wall obtained by the finite element method and the theoretical solution was 5.65%, indicating that the theoretical value was in good agreement with the simulation results. The simplified calculation method can provide reference for the design and calculation of steel plate-concrete composite wall of prefabricated underground silo.