The invention provides a reagent for detecting a Notch signal path as well as a PCR (Polymerase Chain Reaction) detecting method and application thereof. The detecting reagent comprises PCR reaction primers for detecting an ADAM10 gene, an ADAM17 gene, an AES gene, a CBL gene, a CCND1gene, a CD44 gene, and the like, and primers of corresponding internal-reference regulatory genes GAPDH (Reduced Glyceraldehyde-Phosphate Dehydrogenase), ACTB (Beta-Actin) and B2M (Beta-2-Microglobulin). The invention provides the reagent for detecting core molecule changes of the NOTCH signal channel; by virtue of the detecting reagent, genes associated with the NOTCH channel can be quickly detected on transcriptional level by virtue of real-time fluorescent quantitative PCR; on this basis, core molecules and a mechanism of action of a tumor NOTCH signal channel are analyzed and researched, so that an NOTCH regulatory channel of tumor-associated medicaments is quickly and accurately found, and therefore, a powerful tool is provided for screening anti-tumor medicaments, discussing the mechanism of a novel targeted medicament, and the like.