In resent years,integrally stiffened panel has already been a new research direction in aircraft structure design.For a typical integral panel of aircraft,the parameters model of the panel with cracks is established.Three dimensional crack growth trajectories in the skin pad and the stiffener are then simulated.Changes of the stress intensity factor in the skin,the pad and the stiffener,as cracks grow,are analyzed by use of finite element method.The conclusions drawn in this paper can be used for damage tol...