Abstract: The dynamic delaminating influences on the natural frequencies of the laminated beams are investigated in this paper. The relations between spall and the first eight natural frequencies are given for different boundary conditions. It is found that the delamination affects the natural frequency of 1st and 2nd order. The degree of effect the delamination on natural frequency depends on boundary conditions. The 3rd and higher frequency of the laminated beams are found to be insensitive to the delamination. These results can be useful in structural design and nondestructive detection.