Summary In this study, we investigate the reported ultrasonic measurements of core samples of organic shale and our lab measurements. We focus on Vp/Vs ratios, P-impedance, and velocity anisotropies for different types of organic shales. A layered model is constructed to explain why the silica-rich shales tend to have higher S-wave anisotropy and calcareous shales tend to have higher P-wave anisotropy. Hence, ratio may be potentially treated as an indicator for mineralogical composition in shale reservoirs. We also observe linear trends between Thomsen's parameters, / So rock physics models developed for clay-dominated mudstones are inappropriate and cannot be applied to organic shale.