As　one　of　the　most　exciting　building　blocks,　DNA　has　gained　increasing　attention　in　the　construction　of　promising　nanostructures　for　various　biological　and　medical　purposes.　In　this　contribution,　we　have　developed　an　easily　constructed　DNA　nanoassembly-based　biosensing　system　that　consists　of　one　signal　hairpin　probe　(SHP)　and　one　label　-free　hairpin　probe　(LHP)　for　target　p53　gene　analysis.　The　probes　of　SHP　and　LHP　were　designed　to　be　incapable　of　interacting　with　each　other　in　the　absence　of　the　p53　gene.　When　the　target　gene　is　introduced,　the　3＇　end　of　SHP　(or　LHP)　hybridizes　with　the　middle　region　of　LHP　(or　SHP),　leading　to　polymerase-sustained　DNA　nanoassembly.　Because　one　target　species　can　exhaust　many　building　scaffolds　to　execute　the　programmable　nanoassembly　in　one-pot　approach,　the　fluorescence　intensity　of　SHP　is　greatly　enhanced　in　the　presence　of　target　gene　in　a　simple　and　robust　manner.　The　practical　applicability　was　successfully　demonstrated　by　screening　target　gene　extracted　from　cancer　cells.　We　believe　this　intriguing　sensing　strategy　and　desirable　assay　ability　would　provide　new　opportunities　to　develop　versatile　biochemical　analysis　methods.