Abstract: The personnel air lock is one part of the inner reactor containment, which is the third layer of the barrier. Persons and small equipment can pass the personnel air lock when the reactor is running or hot shutdown without damaging the containment sealing function. The personnel air lock should prevent the unacceptable release of radioactive material. Mechanical analysis for personnel air lock in third-generation nuclear power plants is carried out using ANSYS finite element analysis software. A three-dimensional model of the personnel air lock is built to give the various working parameters. The impact of civil works（the forced displacement） is considered, and the stress distribution and the deformation by simulation are obtained.