Abstract: A new filtering algorithm for InSAR interferogram is proposed.First,the raw intergerogram is mapped to unit vectors.Then the vectors are decomposed to two parts: the sine signal and the cosine one.Secondly,the sine and the cosine signals are filtered by wavelet threshold method.Finally,the filtered interferogram is calculated by the filtered sine and cosine signals.In order to evaluate the precision of filtering,a new evaluation method is presented,which uses the RMS of the phases between interferograms before and after filtering.Different types of interferograms are employed in experiments.The results show that the proposed filtering method is valid.