The transport properties of one-dimensional photonic crystal consisting of single-negative materials, with an impurity layer, are studied by using the transfer matrix method. The results show that the defect mode appears in the forbidden band of the photonic crystal when there is a defect layer. The position of defect mode moves from the high frequency of the forbidden band to the low frequency with permeability μ increasing. And the position of defect mode moves from the low frequency of the forbidden band to the high frequency with permittivity ε increasing. These characteristics can be used to dynamically control the optical transmission.