A kind of novel photonic crystal fiber grating based on structural change is researched. The influence of refractive index brought by structural change is studied by using multipole method. The relation between effective refractive index and collapsed cladding pillars is gotten. The model of structural changed photonic crystal fiber grating is built. Furthermore, the influence of cladding layers of pillars and the degree of collapsed pillars are discussed. It is shown that periodic collapsed pillars can form grating, and that not only the extent of collapsed pillars, but also the collapse envelope has influence on the magnitude and distribution of effective refractive index. As the layers of pillars increase, the resonant wavelength shows blue shift, the grating has wider bandwidth and weaker resonance intensity. Under the same fiber structure, resonant wavelength shows red shift and grating has narrower bandwidth with increasing the extent of collapsed pillars.