Abstract: Matched-field processing (MFP) and matched-mode processing (MMP) are passive range and depth source localization technique that have been extensively used in shallow-water environments.This paper presents a new technique of normal-mode filtering and simulated results on source localization of a short horizontal array.The results of MMP are compared to those obtained by conventional MFP.The simulated results indicate that for MMP source location the resolution is higher than that of MFP's and the sidelobe rejection is improved,the expense of the computational time is less.The effects of system mismatching are also given.