Until　now,　corona　virus　disease　2019　(COVID-19)　remained　to　be　an　enormous　threat　for　global　health.　As　one　viral　illness　induced　by　severe　acute　respiratory　syndrome　coronavirus　2　(SARS-CoV-2),　versatile,　rapid　and　sensitive　method　for　SARS-CoV-2　detection　in　early　stage　is　urgently　needed.　Here,　we　reported　an　ultrasensitive　and　visual　in-one-tube　detection　method　which　could　be　accomplished　within　half　an　hour　from　sampling-to-result.　By　integrating　all　reactions　in　one　tube,　liquid　handling　steps　were　omitted　and　amplicon　contamination　could　be　totally　avoided.　Magnetic　beads　were　employed　to　achieve　the　fast　extraction　of　viral　nucleic　acid　and　increase　the　sensitivity.　Using　portable　thermocycler　and　blue　light,　the　fluorescent　results　could　be　directly　observed　by　naked　eyes.　The　proposed　method　is　of　higher　specificity　and　sensitivity,　nearly　at　single　molecule　level.　More　important,　results　demonstrated　100%　positive　detection　rate　for　40　clinical　samples,　which　was　consistent　with　standard　RT-PCR.　Thus,　our　method　is　considerably　simple,　rapid,　sensitive　and　accurate,　holding　great　promise　for　the　instant　detecting　of　viruses　including　SARS-CoV-2　and　the　next　generation　of　molecular　diagnosis.　©　2022