Taking the clamped slab as the study object,the research simulated the structural damage by changing the elastic modulus of elements and detected the damage based on the vibration modes,the frequency,and the mode curvature difference respectively.The results show that the vibration modes and the frequency changed too little to identify the damaged location in the thin slab with small area damaged,while the curvature mode difference of the damage element changed obviously.Therefore the location of the structure damage can be identified exactly by using the method of the curvature mode difference.