Aptazymes are a new artificial synzyme, selected from the random oligonucleotide sequence libraries against various of effector molecules. They own the advantages of an aptamer(the receptor site) and the ribozyme (the catalytic active site). Moreover, aptazymes as catalytic molecular beacon provide a new orientation for the quantitative analysis of effector molecules. Aptazymes not only have the application in genomics and proteomics, but also have potential applications in biosensor and DNA AND gate.