The beam spot will break up into some cracks when the beam propagates through the turbulent atmosphere. The characteristic of the cracked beam spot are studied statistically for different emitting beam shapes and beam qualities, and with different turbulent effects. It is shown that, with the degeneration of the beam spot and the turbulence being stronger, the total radius of the beam spot and the number of the fragments will increase; meanwhile the radius of the fragments will keep invariable almost: about the radius of the bucket which contain 63% of the total energy. In order to understand this phenomenon, four different kind of situations: the diffraction of thin ring, diffraction of double apertures, decomposing the field into the superimposition of different frequencies and the propagation of solid beam with strong turbulent effects, are analyzed and primary explanation are given.