N-6-Methyladenosine　(m(6)A)　stands　out　as　the　predominant　internal　modification　in　mammalian　RNA,　exerting　crucial　regulatory　functions　in　the　metabolism　of　mRNA.　Currently　available　methods　have　been　limited　by　an　inability　to　quantify　m(6)A　modification　at　precise　sites.　In　this　work,　we　screened　a　Bst　2.0　warm　start　DNA　polymerase　with　the　capability　of　discriminating　m(6)A　from　adenosine　(A)　and　developed　a　robust　m(6)A　RNA　detection　method　that　enables　isothermal　and　ultrasensitive　quantification　of　m(6)A　RNA　at　single-base　resolution.　The　detection　limit　of　the　assay　could　reach　about　0.02　amol,　and　the　quantitative　accuracy　of　the　assay　was　verified　in　real　cell　samples.　Furthermore,　we　applied　this　assay　to　single-cell　analysis　and　found　that　the　coefficients　of　variation　of　the　MALAT1　m(6)A　2611　site　in　glioblastoma　U251　cells　showed　over　20%　higher　than　in　oligodendrocytes　MO3.13　cells.　This　method　provides　a　highly　sensitive　analytical　tool　for　site-specific　m(6)A　detection　and　quantification,　which　is　expected　to　provide　a　basis　for　precise　disease　diagnosis　and　epigenetic　transcriptional　regulation.