The invention relates to a fluorescent quantitative detecting method for CYP2C19 genotyping fluorescent and a diagnostic kit. At present, CYP2C19 genotyping techniques at home and abroad are mainly RFLP technique and ALA technique which determine genotypes according to the size of a DNA fragment, with the disadvantages of time-consuming operation and low flux. The invention provides a novel point mutating or SNP detecting method which utilizes the ASA combination primer sequence designed for the polymorphic loci of the CYP2C19 gene exons 4 and 5, the referential ASA primer combination or the degenerated primer sequence for quality control, specific TaqMan-MGB probe sequences for amplified products, an ASA amplifying reaction method, the amplifying reaction result of real-time fluorescent quantitative detection, the fast analysis of mutation locus type and genotyping. The quantitative detecting method has the advantages of time saving compared with a conventional ASA method, no need for electrophoresis detection, fastness, accuracy, and the like, and can be used for detecting other drug-metabolizing enzymes, or more extensive genetic variation or mutation.