Abstract: Researches of compositions of individual hydrocarbon inclusion have attracted much attention in the world.Connecting laser micropyrolysis system to gas chromatography-mass spectrometry system by means of sample input and enrichment system,analysis instrument for compositions of individual inclusion has been made.Individual inclusion is cracked with laser.Hydrocarbon is concentrated and gas chromatography-mass spectrometry studies are carried out.Analyses of C₆₊ in individual inclusion have come true for the first time.Inclusions of different stages are studied respectively,providing significant ways for studies of petroleum accumulation and evolution history in marine facies superimposed basins.