Abstract: In this article,using a fast iterative method of mode decomposition,source range-depth localization performnces of matched-mode processing (MMP) for three kinds of vertical array (short,sparse,and short-sparse array) in shallow water with a downward refraction soulld——speed profile ofthe summertime are discussed.According to the characteristic of this method,the accuracy of mode decomposition is measured by its root-mean-square error.The numerical simulated results illustrate thatthe accuracy of source range and depth estimation is raised and the sidelobes are suppressed effectively.The shortrsparse vertical array not only has shorter length and fewer hydrophones,but also can beapplied to dthereni sea areas with variable depth,so it is the optimum type of vertical array in theengineering project of the passive source localization.