Methane production and oxidation in paddy fields not only affects methane emission from the fields, but also influences isotopic carbon composition of the methane emitted into the atmosphere; but in turn, by determining isotopic carbon composition of emitted methane, quantitative study of the processes of methane production and oxidation is made feasible. Since the 1980s, the stable carbon isotope technique has been widely applied in the research on methane in paddy abroad. By introducing the fundamental principles of the stable carbon isotope technique and their application in the research on methane production and oxidation in paddy fields, and discussing some uncertain factors of its application in the study, the paper provides the study of methane emission from paddy fields in China with a new strong means.