Abstract: The Paleocene?Neocene in Yuejinsihao in Qaidam basin is a complete cycle of first?grade sequence, with coarse?fine?coarse grain sizes from the top to the bottom, and can be further divided into three secondary?grade sequences. According to related paleontologysedimentary structure, grain size, geochemical, lithologic and electrical characteristics, four sub?facies in this area could be recognizedsuch as shallow lake, shore lake, delta plain and delta front. Accordingly, six microfacies can be classified, including mud flat, lime mud flat, marl flat, algal hill, branch channel, branch inter?sag and splay. The first and second sequences in the secondary?grade one are obviously influenced by Faults No.Ⅶ and No.Ⅷ, and deposits and reservoir physical property of the upthrow and downthrow have great differences, so the favorable reservoirs could be distributed in the upthrow