The Neogene and Paleogene sedimentary facies and microfacies inwestern Qaidam Basin were divided into seven types as follows: pluvial，subaqueous alluvial fan，fluvial channels and flood plain，shorelake，shallow lake，relativelydeep lake and delta based on well data of logging，lithology and testing analyses.Types and distribution of sedimentary facies are divided into three zones: (1) pluvialalluvial fanfan deltafluvial channels and flood plainlake facies in the steep zone of western Altun mountain front; (2) pluvialalluvial fanlake facies in the steep zone ofmiddle Altun Mountain front; (3) pluvialfluvial channels and flood plaindelta in the zone of Kunlun Mountain frontSedimentary facies not only influence composition and textureof clastic rock，but also porosity and permeability and hydrocarbon accumulation of clastic rockThe content of stable quartz and cement increases，the content of fragment and matrix decreases from pluvial，subaqueous alluvial fan，fluvial channels and flood plain，delta to lake facies，the sorting and roundness of grain get better and better，size ofgrain gets finer and finerPorosity and permeability of fluvial and delta clastic rocks are best in the shallowburied strata of the west Qaidam BasinIn the deeplyburied strata，porosity and permeability of deltaic clastic rocks are the best，those of alluvialclastic rocks are the second，and those of lacustrine clastic rocks are the worstHydrocarbon accumulation is richest in fluvial and deltaic clastic rocks，and is relatively poor in the deeplyburied strata