Numerical calculating on the defect mode in the one-dimensional (1-D) photonic crystal by the optical transmission matrix method was studied. We calculated and analyzed the relationship between refractive index of the defect layer and wavelength of the defect peak and the relationship between defective layer’s thickness and wavelength of the defect peak. It is found that with increasing of the defective layer’s thickness, the wavelength of the defect peak increases linearly. But much more defect peaks would be found when defective layer’s thickness comes to a constant. Additionally, refractive index of the defect layer increases linearly with the increasing wavelength of the defect peak. So, a more effective method of measuring refraction and dielectric constants in microwave field is p