Early diagnosis of cancer can increase the survival rate of patients. Minimally invasive liquid biopsy can avoid the problems of invasion and heterogeneity of traditional tumor biopsy methods, also is becoming a new approach for cancer diagnosis. In addition, DNA methylation as a marker to predict the occurrence and development of cancer has aroused more and more researchers" interest. But the traditional DNA methylation detection methods usually possess poor sensitivity and false positive. In recent years, digital PCR technology has been used for quantitative detection of DNA methylation because of its super sensitivity, better accuracy and the advantage of absolute quantification of nucleic acids without standard curve. Firstly, this review introduced the relationship between DNA methylation and carcinogenesis, then summarized the traditional detection methods of DNA methylation and their applications in clinical cancer early diagnosis. Secondly, the digital PCR based on different methods of nucleic acid sample dispersion and its advantages in the detection of DNA methylation are elaborated. Also, this review summarized the specific steps of using digital PCR to detect DNA methylation in body fluids for cancer diagnosis. Finally, we reviewed the research results and application progress of digital PCR in cancer DNA methylation detection. The possible challenges in the future of digital PCR in cancer DNA methylation detection are put forward and the opportunity of digital PCR in cancer liquid biopsy are prospected.