In order to directly study the physical cause of this phenomenon, we have studied the functional relationship between the amplitude of light and its position in this photonic crystal. Most of the injected light waves are located in photonic crystals, such as light with λ = 4.5, which is within the passband of ordinary photonic crystals with Na/Nb = 3.4 and Da/dA/dB=0.286. When the photonic crystal is disturbed, it will be positioned as shown in Figure 3(a). But for a certain wavelength of light wave, its amplitude is Bloch waveform, which is obviously misplaced (or extended) [see Figure 3(b)]. It should be pointed out that the positioning phenomenon and dislocation phenomenon are the results of Maxwell equation and perturbation purity. In other words, these phenomena are observed numerically, but the positioning and dislocation conditions are not introduced in theory.