Abstract: The reservoir characteristics of lacustrine dolomite in Hari sag are studied by means of core observation,well logging interpretation,scanning electron microscope and conventional reservoir property analysis.The results show that the dolomite reservoir in Yiner basin is well developed.The reservoir is mainly of argillaceous dolomite,and the dissolution pores and interlayer fractures are well developed.The average porosity is 6.73%and the average permeability is 0.025×10~(–3)μm~2,which belongs to ultra-low porosity and ultra-low permeability reservoirs.The genesis mechanism of dolomite is mainly‘microbial dolomitization’and‘evaporative pump action’.