The underground granary can take full advantage of the underground space, it has better fireproof, anti-toxicity, explosion-proof and other properties. In the meantime, the underground silo can use the shallow geothermal energy to realize quasi-low temperature storage. With the advantages of energy-saving, low-consumption and grain quality-ensuring, it plays a significant role in ensuring the grain safety and sustainable development of China. This paper adopted the combination of engineering full-scale test and numerical analysis to carry out engineering tests at different construction stages of the large underground concrete silo, and conducted engineering tests and numerical simulation on the mechanical properties of the silo wall at different construction stages to verify the rationality and validity of the numerical analysis method. Furthermore, the mechanical properties of the wall of the most unfavorable working conditions under the combined soil and water pressure were numerically analyzed. The results show that the internal forces of the numerical simulation results of the silo wall were in good agreement with the experimental results, which verified the validity of the numerical method, the radial stress of the silo wall was highest at the bottom of the silo wall, and the hoop stress was highest at about two-thirds of the top of the silo wall. This method can provide reference for the mechanical analysis and structural design of similar underground reinforced structures.