Based on the damage mechanics theory, summarized a new dynamic reliability calculation method with
explicit physical meaning, which is used for researching structural dynamic reliability on cyclic stress. By using of the
model of stress-strength interference, ignoring the effects of erosion and aging on the strength degradation, only consider
that the change of damage leads to the effective stress increasing. Take the intensity as a random variable, view stress as a
random variable which was changed with the times of loading, combine physical experiments and simulation with
sampling, analog the dynamic reliability curve of the casting crane hook on the beam with the change of loading times.
Analyze the changing trends of dynamic reliability under the condition of different distribution parameters of cross
section at the 420 °C. The results suggested that the reliability showing a downward trend when the life is about 85%, the
dynamic reliability curve has a typical bathtub curve of the latter two steps.