Recent　years,　several　techniques　have　been　proposed　to　preserve　the　user　location　privacy　in　road　networks.　Some　of　the　existing　techniques　may　suffer　replay　attack,　and　leads　to　leaking　the　user　location　privacy.　The　existing　technique　to　resist　replay　attack　is　add　a　randomize　step　into　the　cloak　process,　which　may　be　unquestioning.　In　this　paper,　we　propose　a　grouping-based　method　to　prevent　replay　attack　by　dividing　the　segment　set　to　form　cloaked　set.　The　experiment　result　shows　the　effectiveness　and　feasibility　of　our　algorithm.　©　2012　IEEE.