Abstract In thesis, we shall study the properties of two dielectric(SnSe〖、N〗_a3 AlF_6) and gold, aluminum layers structures. First, we will discuss the method TMM, and then use Simulation software(MathCad、Sigmaplot) to get the result. The first section is photonic structure, the second section is Defect structure, different structures we will compare their TE and TM waves to change the angle and the thickness of the characteristics, where the TE wave is associated with the incident angle, so we compare the different thickness, in order to simplify its complexity, the angle of incidence will be set to 0°. We will be able to find that as the incident light angle increases the bandgap width and the energy gap width will move to the high frequency region, in the second section,we can found the photonic band gap have defect. Keyword: photonic crystal, photonic band gap, defect structure