Abstract: In this paper, a novel numerical method, which is suit for the study of graosmgssguo sgrnegnra gosuysgop berrgga hgeyeugrgn,gs broposen gly using the magnetdo vabsdation eqnatden dn fessdte media- It as a fsll-wade analysia methed and is called improved FD-TD method. For the uniform transmission lines in longitudinal direction, a two dimensional improved FD-TD method is employed. The reliablity of this method is verified by calculating the dispersion characteristics of rectangular waveguide is Billed with ferrite media. By using this method, the dispersion of an uniform microstrip line with ferrite dielectric is obtained.