<p>The shale from the Ganchaigou Formation in the Qaidam Basin was deposited in a saline lacustrine environment with strong heterogeneity. Understanding the variations of seismic rock-physic properties plays a crucial role in evaluating reservoir “sweet-spot” and quantitative seismic interpretation. This study aims to clarify the impact of the sedimentary environment on the physical properties of the shale samples from the upper member of the Lower Ganchaigou Formation by combining rock physical properties measurement, reservoir petrology, and sedimentary sequence analysis. The results indicate that differences in sedimentary environments controlled the compositions and microstructure, determining the elastic properties of the Ganchaigou lacustrine shale samples. As the increasing of salinity, the dominant lithology of sediments changes from layered mudstone to laminated argillaceous shale, then to laminated calcareous shale, and finally to layered dolomite, resulting in the sequential increase of velocity and decrease of Vp/Vs ratio. In addition, the load-bearing frame of interbedded sandstone consists mainly of quartz and feldspar minerals, reducing the Vp/Vs ratio significantly. The velocity anisotropy of the Ganchaigou lacustrine shale samples is influenced primarily by the preferred orientation of clay platelets and is positively related to the content of clay. Compared with layered samples, clay minerals in laminated shale samples are more easily aligned along with the bedding plane owing to mechanical compaction, and the differences in elastic properties between laminae increase additionally the velocity anisotropy. The velocity anisotropy of samples is slightly affected by the amount of TOC due to the low content and the dominant lens shaped. The research results can provide a theoretical basis for predicting the “sweet spot” and interpreting seismic data of the Ganchaigou lacustrine shale reservoir.</p>