This article takes the prestressed concrete containment vessel of a third-generation advanced pressurized water reactor nuclear power plant in China as the research background, and systematically studies the failure development mechanism of each component material of the containment under the coupling effect of high temperature and high pressure. At the same time, research on the problem of ISP48 by the French Institute for Radiation Protection and Nuclear Safety (IRSN) and the failure criteria specified in the US standard RG1.216. The research results indicate that the ultimate bearing capacity of the containment is ultimately controlled by the sealing performance of the steel liner. When the steel liner experiences functional damage, the containment structure usually maintains its structural integrity. The sealing failure of the steel liner occurs near the equipment hatch, and the development mechanism of the failure is that the concrete near the equipment hatch produces a through type crack from the outside to the inside. When all the concrete near the hatch cracks, the deformation of the steel liner will rapidly increase until it is tearing. At this time, only a small area of prestressing tendon and rebars will yield. The ultimate bearing capacity at this moment is 1.12 MPa, which is approximately 2.67 times the design pressure.