Abstract: Several methods of destructive post-irradiation examination(PIE) including microstructure observing and measurement of mechanical properties of irradiated fuel rod were introduced. Optical microscope, transmission electron microscope(TEM) and scanning electron microscope(SEM) were described. Tensile test, tube burst test and creep test of irradiated cladding in hot cell were discussed. The changes of mechanical properties of cladding before and after irradiation were compared. These methods contribute to understand irradiation behavior of fuel, cladding and structure components and supply proof for increasing burnup.