The distributed parameters of the transmission lines have the significant impact to the signal propagation.In the conventional method of the distributed parameter extraction,the discontinuity of inverse trigonometric or hyperbolic can arise the problem about phase ambiguity which causes significant errors for transmission models.A difference iteration method (DIM) is proposed for extracting distributed parameters of high frequency transmission line structure in order to overcome the phase ambiguity in the conventional method (CM).The formulations of the proposed method are first derived for two-conductor and multi-conductor lines.Then the validation is performed for the models of micro-strip transmission line.Numerical results demonstrate that the proposed DIM can solve the problem about the phase ambiguity and the extracted distributed parameters are accurate and efficient for a wide range of the frequencies of interest and line lengths.