The photonic crystals (PCs) are structures that periodically arranged by two or more different dielectric material. There are bnadgaps in its frequency band, and bandgaps will be changed when we change the structure (such as material, arrangement) or incident angle. In this thesis, we discuss some methods for bandgap modulation in 1-D PCs by change the structure. Above, we have described in Chapter 1. In here, the basic structure we used is (AB)nA, when AB denote the unit cell, each representing two different material, n is the number of period. In Chapters 3, 4 and 5, we use “power-law” and “linear” and “disorder” three methods to modulate the structure, and we chose the best one by observe their effect. Then we change the material to match the best method, and observe it again in Chapter 6. Finally, in Chapter 7, we make a conclusions.