Using MBPE technology can quickly predict the approximation of the frequency response of transmission lines' scattering field. However, equal interval sampling method is usually used in the calculation of transmission lines' scattering field, it results a possibility that the sampled data may be with lack of important points, which makes the fitting results difficult to control, or samples duplicated information to increase the amount of calculation. In order to calculate more accurately, the adaptive sampling algorithm is introduced here. In the fast solution of frequency response of transmission lines' scattering field, it greatly improved the accuracy of results. Finally, compared with those of the traditional interval sampling methods, the results of using adaptive sampling algorithm were in line with the actual situation.