Sensitive and efficient detection of RNA methylation sites is considered an integral part of epigenetic assessment. Contrary to previous studies on the detection of RNA m5C or m6A methylation alone, this study innovatively designed a biosensor capable of detecting RNA m5C or m6A methylation at the same time. Substances with specific electrochemical reactions such as ferrocene (FC) or methylene blue (MB) were modified onto the hairpin probe. When the hairpin probe was activated under specific conditions, it triggered a dendritic nonlinear hybridization chain reaction (HCR), which resulted in signal amplification. Gold (Au) and iron tetraoxide (Fe