||The present review article to discuss briefly about the construction and working mechanism of the hyphenated technique GC-MS. Here the importance of the hyphenated technique in the drug resolution was determined. GC with low resolution electron ionization (EI)-MS was used, together with confirmation with chemical standards, for identification work. The method was successfully applied in many fields like forensic department and environmental analysis. It is also used in the anti-doping analysis. The combines the features of gas-liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC - MS include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of unknown samples. GC - MS has been widely heralded as a "gold standard" for forensic substance identification because it i s used to perform a specific test.