The invention belongs to the technical field of biomedicine. Based on the fact that the abnormal methylation of genes are involved in the generation and development of tumors, the invention aims to overcome the defects of a methylation sensitive restriction enzyme method, a bisulfite sequencing method and a methylation specificity PCR (Polymerase Chain Reaction) method, and provide a methylation quantitative detection method of the PCDH8 (Protocadherin-8) gene, with simple and convenient operation and high sensitivity. The detection method comprises the steps of: taking pancreatic cancer tissues, extracting DNA to prepare a standard curve sample of ACTB (Actin, Beta), and preparing a standard curve sample of PCDH8; extracting the DNA of a tissue to be detected, carrying out chemical decoration, designing a methylation primer and a probe for a CPG island in a human PCDH8 gene promoter area, and designing a BSP primer and a probe for a CPG island in a human reference gene ACTB promoter area, carrying out real-time quantitative PCR on the DNA subjected to the sulfite treatment by using a Taqman-MGB real-time quantitative PCR method, and calculating out a quantitative value on the methylation degree of a PCDH8 gene. The method has the advantages of rapidness, correctness and high sensitivity.