Abstract: Using a modified Finite-Difference Time-Domain method based on Z-transform (Z-FDTD), that is, frequency domain constitutive relations of bianisotropic dispersive media are expressed in Z domain. Then Z domain relations are converted to time domain by using properties of Z-transform method, and FDTD equations in discrete time domain can be obtained. The electromagnetic wave propagation characteristic of bianisotropic dispersive media is analyzed. Omega medium is considered as a classic example of bianisotropic dispersive media. The algorithm is used to calculate the reflection and transmission of co-and cross-polarized electromagnetic waves from omega slabs, illuminated by normally incident plane waves. The Z-FDTD results are validated by means of comparisons with analytical solutions. Finally the electromagnetic scattering characteristic of bianisotropic dispersive media is analyzed by this method.