Abstract: Sequence stratigraphic studies with high resolution were carried out in the Lower Ganchaigou Formation in the Yuejin Slope of the Qaidam Basin by means of drilling/logging,seismic and natural gamma ray spectrometry logging methods.The Lower Ganchaigou Formation was divided into 2 sections vertically.9 sequence boundaries and 8 fourth-order sequences were identified.Based on core observation,the Yuejin Slope was a braided-river delta,and the study area was mainly of braided-river delta front facies.Combined with the studies of sand body distribution,structure and seismic inversion,2 possible favorable zones of lithologic trap were predicted in sequence Ⅲ of the Lower Ganchaigou Formation.