We report on the properties of light transmission in one-dimension photonic crystals with defects of nonlinear dielectric material, photonic crystals have simple and complex period dielectric structure with multi-unit layer. In particular, we are interested in the transmittance of defect mode and the intensity enhancement factor of localized light. By the transfer-matrix method, we can calculate the electromagnetic waves transmission through a photonic crystal, the intensity enhancement factor of localized light can be obtained. The method calculated the transmission properties normal incident on a finite thickness slab of material. The numerical calculation shows that the transmission with defect layer of nonlinear dielectric material can induced to bring about change by the input intensity of light, and the change of the transmission shows the bistability. For simple and complex period dielectric in PC, if the threshold of input intensity be satisfied, the properties should be emerged easier. For complex period dielectric in PC, the transmission can show the property of complex results. When the total transmission is big, the bistability is also displayed. In addition, the character is seen to determine by the saturation absorption coefficient of the defect medium, the refractive index ratio and the number of layers.