Abstract: In the recently-developed laser ablation GC-MS analysis instrumentation for oil-bearing inclusions,excimer laser of 193 nm wavelength is employed to ablate host minerals (i.e.quartz) so as to release the oil compositions trapped inside.The compositions are cryogenically trapped on line and then analyzed with GC-MS.Geochemical information of crude oil in single fluid inclusion can be obtained with this method.Moreover,similar to traditional methods,various compounds such as gasoline,alkane,iso-alkane,and cyclo-alkane as well as monoaromatics,dicyclic aromatics and polyaromatics can be monitored with this new method.