The　development　of　rapid　approaches　to　detect　prognostic　markers　is　significant　in　reducing　the　morbidity　and　mortality　of　cancer.　In　this　paper,　we　describe　a　rapid　and　specific　biosensing　platform　for　target　DNA　(p53　gene　as　a　model)　detection　based　on　reverse　strand　displacement　amplification　(R-SDA).　When　the　p53　gene　is　added,　multifuctional　molecular　beacon　(MMB)　is　unfolded　via　the　hybridization　with　p53　gene.　With　the　assist　of　Klenow　fragment　(KF)　and　Nt.BbvCI　(the　nicking　endonuclease),　p53　gene　recycling　could　be　initiated　and　considerable　amount　of　complementary　sequences　for　the　MMBs　(Nicked　fragments,　NFs)　could　be　formed,　generating　enhanced　fluorescence　signal.　Using　this　amplification　strategy,　the　proposed　biosensor　displays　the　detection　limit　of　1　nM　and　a　wide　linear　range　from　1　to　100　nM,　even　if　only　one　type　of　probe　is　involved.　Notably,　remarkable　detection　specificity　for　single-base　mismatched　target　p53　gene　is　achieved.　Moreover,　the　described　biosensor　also　exhibited　the　stability　in　real　biological　samples　(human　serum).　The　rapid　detection　strategy　can　be　performed　less　than　30　min　without　harsh　reaction　conditions　or　expensive　nanoparticles.　This　biosensor　shows　great　potential　for　application　in　clinic　assay,　especially,　for　early　cancer　diagnosis.