The improved composition analysis method for grouped fluid inclusion may collect gas, light and heavy hydrocarbons at the same time. Liquid nitrogen is used to freeze samples and break them into single minerals, keeping crystal form unchanged. Ball milling is applied to open fluid inclusion whose components and properties are protected during this process. Composition analyses of free hydrocarbon, adsorbed hydrocarbon and petroleum inclusion in 9 reservoir samples from the Shaya Uplift have indicated that, the compositions of gas and light hydrocarbon in inclusions may be used judge sample maturity. The biomarker and carbon isotope of liquid hydrocarbons may show the differences in sedimentary environment and accumulation.