Acute　myocardial　infarction　(AMI)　is　a　major　health　problem　leading　to　high　rates　of　mortality　and　morbidity.Biomarker　cardiac　troponin　I　(cTnI)　has　shown　high　sensitivity　and　specificity　towards　AMI　detection,and　has　been　regarded　as　＂gold　standard＂.An　ultrasensitive　method　to　detect　cTnI　with　low　concentration　in　human　fluid　is　essential.In　this　paper,we　developed　an　aptamer-based　assay　coupled　with　rolling　circle　amplification　(RCA)　and　molecular　beacon　probe　for　sensitive　detection　of　cTnI.In　this　strategy,aptamer　acts　as　a　bridge　to　communicate　between　oligonucleotides　and　cTnI.RCA　reaction　produces　a　single-stranded　tandem　repeated　copy　of　the　circular　template,which　are　recognized　by　fluorescence　molecular　beacon　probe.With　this　strategy,highly　sensitive　and　specific　detection　of　cTnI　was　realized　with　the　lowest　detectable　concentration　of　7.24　pg/mL.The　developed　aptamer-RCA　assay　can　be　a　promising　tool　in　clinical　samples　analysis.The　assay　can　also　analyze　other　disease-related　biomarkers　by　replacing　the　aptamer.