Abstract: Based on the studies of chemical composition and features of Raman spectrum(LRM),together with the relationship between the displacement values(ν) of the major chemical composition CO₂,CH₄,H₂O and the buried depth of fluid inclusion.the author has shown that: 1)It can be proposed that there are at least eight types and four assemblages inclusions occurred in the Lower Ordovician reservoirs;2) The richness of CO₂-,CH₄-hydrocarbon and H₂O-CO₂ brine inclusion are dominant in those assemblages;3) In a single inclusion,the content of methane in gas phase increase initially but decreases at later with increasing that of depth;4) The displacement value(ν) and content of methane simultaneously decrease with the buried depth of samples;5) The displacement value(ν) of water presents a non-line covariance with the depth of samples;6) The contents of methane in gas phase demonstrated a negative linear covariance of its contents carbon dioxide;and the author believed that those parameters can be used as the indicator of maturity of hydrocarbon emplacement.