Abstract: In the pool fire environment, it is very easy to cause failure fracture and explosion accidents in the common vertical vault tanks under the combined action of flame thermal radiation and convection, which poses a huge threat to the safety of rescuers and oil storage tanks nearby. Based on the failure mechanism of oil storage tank under the pool fire, a 5 000 m³ vertical vault oil tank with frangible roof structure was studied with ANSYS and LS-DYNA softwares in combination. Specifically, the dynamic failure process under pool fire was numerically simulated. As shown in the results, the internal pressure of tank increases under the pool fire, and the fracture failure arises firstly at the frangible roof structure of the tank, with the maximum stress reaching 294.2 MPa. In addition, the maximum temperature is distributed in the gas zone, up to 348.7℃. In order to verify the feasibility of numerical simulation analysis on dynamic tank failure, a tensile test on weak connection was designed, which provides a theoretical basis for safety rescue under the pool fire. Generally, the research results, with safety warning provided for firefighting and disaster relief of tank, are significant to guide the disaster relief, reduce the loss of life and property, and guarantee the safety of national oil reserve bases.