The invention relates to an asymmetrical hairpin probe and an application thereof, and belongs to the biological detection field. The asymmetrical hairpin probe consists of a target 
nucleotide distinguished sequence and a 
palindromic sequence; under the condition of no target sequence, the asymmetrical hairpin probe is under the metastable hairpin structure; once a target sequence to be detected is added, chain-type 
polymerization reaction free from the participation of 
enzyme is triggered; the target 
nucleic acid distinguished sequence part of the asymmetrical hairpin probe is combined with a corresponding target 
nucleic acid locus; rest probes are pairwise renatured into parts of double-chain probe of which the two ends are both provided with the 
palindromic sequence; and during 
molecular recognition hybridization, a detection 
signal is substantially enhanced so as to quickly detect the target sequence to be detected. According to the 
chain reaction technology of the asymmetrical hairpin probe, the high specificity of 
molecular hybridization and high efficiency of 
chain type polymerization are artfully combined, and free energy released by 
DNA (
deoxyribose nucleic acid) 
polymerization is used for driving molecular 
cascade amplification. The asymmetrical hairpin probe has the advantages of simple 
reaction system and high detection efficiency, and the laboratory 
pollution problem existing in the traditional technology, such as PCR (
polymerase chain reaction) and the like, can be effectively avoided.