It is very important in the detection of gas isotope abundance for numerous fields including industrial production, biomedicine, and geological surveys, as it facilitates applications such as online safety monitoring in industries and real-time non-invasive clinical diagnoses derived from the analysis of human exhaled gases. This paper first underscores the extensive application potential of isotopic gas detection technology, highlighting its value and utilization. It then delineates five pivotal isotope abundance detection methodologies encompassing mass spectrometry and spectroscopy-namely, mass spectrometry, photoacoustic spectroscopy, tunable semiconductor laser absorption spectroscopy, cavity ring-down spectroscopy, and cavity-enhanced absorption spectroscopy. This paper elucidates the underlying principles of these techniques and sheds light on the recent advancements in isotope gas detection research. Subsequently, a comparative analysis of the performance of the five isotopic gas detection techniques is undertaken to discern their respective merits, limitations, and optimal application environments. Lastly, this paper offers insights into the prospective avenues for future research in isotopic gas signature analysis.