Abstract: The carbon isotope analysis technology has become a key means to reveal the genesis, accumulation, enrichment and output of oil and gas, with the in-depth exploration and development of unconventional oil and gas resources. However, relatively few summaries of the applications on carbon isotope analysis technology has been made in the geological research of unconventional oil and gas. By clarifying the process and key parameters of carbon isotope analysis, the authors in this paper have sorted out the application directions in the geological research of unconventional oil and gas and elaborated the existing problems and development directions. The research suggests that carbon isotope analysis can be applied in five key research directions, that is determining the genesis of oil and gas, comparing oil and gas sources, predicting maturity, identifying reservoir connectivity and physical properties, evaluating "sweet spots", and predicting production capacity, which already have good application effects in the field of unconventional oil and gas geology research. At present, several difficulties and challenges existed in the promotion and application of carbon isotope analysis, including insufficient representativeness of samples and pretreatment, lack of uniformity in the standardization system, and the complexity of carbon isotope fractionation. Therefore, the development direction of carbon isotope analysis is moving towards to high precision, in-situ and dynamic monitoring. Meanwhile, carbon isotope analysis also has broad development prospects in scenarios such as carbon emission traceability, CO₂ geological storage, and geothermal integration. The conclusions and understanding above could provide references for the promotion and application of carbon isotope analysis technology in unconventional oil and gas geological research.