The reservoir at the top of Ordovician paleokarst in Liulin，Shanxi，is composed mainly of dolomite and limestone．The porosity rangeg from 0．5 o／／to 13．58 0／／0 with a mean of 5．06％． The permeabihty ranges from 0．012．5 X 10—3tLm2 to 1224×10—3“m2 with a mean of 21．67×10—3 ／zm2．The dolomite that has been reworked。by leaching and dissolution possesses the best reser— voir properties．The most significant reservoir space is solution pores，caves and fissures．Accord— ing to the lithology，features of reservoir space，distribution of carbon and oxygen stable iso- topes，Fe203，MnO，NazO and Sr contents，degrees of order and MgC03 content in dolomite， homogenization temperatures and salinity of fluid inclusions in calcite fiHings，the factors control— ring the development of the reservoir are sedimentary environments and deposition，leaching of fresh water，paleokarstification，dolomitization and fiHing．