A kind of photonic crystal fiber grating based on structural change was studied by using the multipole method and the coupled mode theory, the structure model was built, and the principle was analyzed. The effective refractive indexes of the cladding with seven rings of the hexagonal symmetry air-holes varying with the wavelength were computed. Moreover, the performance differences of the gratings fabricated by the different photonic crystal fibers were compared. It was shown that the periodic air-holes shrinkage could form grating, and the number of rings of the air-holes in the cladding, the duty ratio of the air-holes, the number of rings of the air-holes shrinkage and the extent of the air-holes shrinkage had the important impact on the transmission characteristics of the photonic crystal fiber grating. Furthermore, the functional relationships that the resonance wavelength and bandwidth varied with these parameters were obtained and the rational explanations were given.