The light wave propagation in one-dimensional photonic crystal with multiple defects is studied by eigen matrix method. There are defect modes in the bandgaps. The defect modes are greatly related with the generating form, optical thickness and refractive index of defect. With the optical thickness of impurity changing, the position and number of defect modes change. Keeping the optical thickness of impurity constant, the changing of refractive index of defect leads to the changing of intensity of defect mode, and there is a maximum among them. If the position of impurity arrange in equal distance, then the defect modes arrange in equal distance, too. The creation of defect modes can broaden the bandgaps, especially when refractive index of defect is much different from that of periodical medium. The defect of air can make transmission rate up to one.