A　highly　sensitive　and　selective　colorimetric　assay　based　on　a　multifunctional　molecular　beacon　with　palindromic　tail　(PMB)　was　proposed　for　the　detection　of　target　p53　gene.　The　PMB　probe　can　serve　as　recognition　element,　primer,　and　polymerization　template　and　contains　a　nicking　site　and　a　C-rich　region　complementary　to　a　DNAzyme.　In　the　presence　of　target　DNA,　the　hairpin　of　PMB　is　opened,　and　the　released　palindromic　tails　intermolecularly　hybridize　with　each　other,　triggering　the　autonomous　polymerization/nicking/displacement　cycles.　Although　only　one　type　of　probe　is　involved,　the　system　can　execute　triple　and　continuous　polymerization　strand　displacement　amplifications,　generating　large　amounts　of　G-quadruplex　fragments.　These　G-rich　fragments　can　bind　to　hemin　and　form　the　DNAzymes　that　possess　the　catalytic　activity　similar　to　horseradish　peroxidase,　catalyzing　the　oxidation　of　ABTS　by　H2O2　and　producing　the　colorimetric　signal.　Utilizing　the　newly　proposed　sensing　system,　target　DNA　can　be　detected　down　to　10　pM　with　a　linear　response　range　from　10　pM　to　200　nM,　and　mutant　target　DNAs　are　able　to　be　distinguished　even　by　the　naked　eye.　The　desirable　detection　sensitivity,　high　specificity,　and　operation　convenience　without　any　separation　step　and　chemical　modification　demonstrate　that　the　palindromic　molecular　beacon　holds　the　potential　for　detecting　and　monitoring　a　variety　of　nucleic　acid-related　biomarkers.　©　2018　American　Chemical　Society.