Abstract:In addressing the critical challenge of persistently increasing atmospheric concentrations of greenhouse gases (CO2, CH4, N2O), merely measuring their bulk concentrations has proven insufficient for accurately assessing their diverse sources, sinks, and the complex biogeochemical processes that control their global budgets. The stable isotopic compositions of these gases (such as δ13C, δ18O, δ15N) provide powerful "natural fingerprints", offering unique insights that transcend concentration data alone. These isotopic signatures enable researchers to effectively discriminate between biogenic and fossil fuel emission sources, quantitatively apportion contributions from different anthropogenic and natural processes, and reveal the underlying microbial mechanisms governing their production and consumption across various ecosystems. This comprehensive review synthesizes recent methodological advancements in isotopic analysis techniques specifically applied to greenhouse gases. It critically examines the fundamental principles, technical characteristics, and optimal application scenarios of mainstream analytical methods. These include the established benchmark technique of isotope ratio mass spectrometry (IRMS), alongside rapidly developing optical methods such as Fourier transform infrared spectroscopy (FTIR), tunable diode laser absorption spectroscopy (TDLAS), cavity ring-down spectroscopy (CRDS), and off-axis integrated cavity output spectroscopy (OA-ICOS). The comparative advantages and limitations of each technique are discussed in the context of precision, operational requirements, and field-deployability. Furthermore, the article systematically elaborates on the transformative applications of these isotopic techniques across a wide spectrum of environmental research. Key areas covered include high-precision tracing of urban emission sources, elucidating production and consumption pathways in aquatic ecosystems, constraining carbon cycling dynamics in soils and wetlands, quantifying greenhouse gas fluxes in sensitive polar regions like Antarctic tundra, and providing crucial validation for carbon cycle models that incorporate geological sources. Finally, the review critically discusses the persistent challenges confronting the field, particularly the pressing need for advanced capabilities in in-situ, high-frequency, and simultaneous multi-component isotopic measurements. It outlines promising future research directions, strongly emphasizing that the integration of multi-isotope observational networks with sophisticated atmospheric and process-based models will be paramount for precisely deciphering global and regional greenhouse gas budgets. Such integrated approaches are identified as foundational for formulating targeted and effective emission reduction strategies and for advancing our predictive understanding of the biosphere's response to a changing climate. Close-