The invention relates to a small RNA detection method and a use thereof and belongs to the field of double-stranded small RNA detection. The small RNA detection method comprises the following steps of 1, designing multiple continuous or discontinuous closed RNAs which are complementary with one chain of a small RNA, a reverse transcription stem-loop primer which is complementary with an end 3' of the other chain of the small RNA, and a forward primer and a reverse primer for quantitative PCR, and 2, detecting the small RNA by denaturation, enclosing, inverse transcription and quantitative PCR. The small RNA detection method has simple processes, a low detection cost, a detection limit reaching a femtogram grade, high detection efficiency, strong singularity and high sensitivity. The small RNA detection method can be widely used for quantitative analysis, qualitative analysis and pharmacokinetic analysis of a small RNA drug, for amplification, specific identification and differentiation of a small RNA molecule, and especially for molecular diagnosis, small RNA drug metabolism and small RNA drug functional study.