Abstract: In the singular value decomposition de-noising algorithm, the choice of the effective rank order is of great importance to influence the performance of the de-noising algorithm. To select a more accurate effective rank order, this paper studied the difference of singular value sequence, proposed a new method to determine the effective rank order, applied it to de-noise the time domain transient electromagnetic signal, and raised the output signal-to-noise ratio. Differs from existing rank-determining algorithms, the proposed method cares about the peaks but not the maximum of the normalized difference, chooses the appropriate peak and determines the rank order together with the difference ratio of the singular value sequence. In simulation experiments we found that for two similar peaks of the singular value difference ,the one whose difference ratio is smaller, is more appropriate to be the effective rank order . The proposed method can keep the waveform feature of the desired signal and decrease distortion while de-noising.