Abstract: Based on study and summary of geochemical characteristics of fluid (oil,gas and water) in Wolonghe gas field (including Jiannan field) of the Sichuan basin and Yakela typical block uplift gas fields (Yakela condensate field and Tiergen field) of the Tarim basin,the author considered that fluid's own microcosmic information could more directly revealsituation of oil and gas preservation than the objective environment, thereby do more accurate evaluation of regional hydrocarbon preservation.