<p>Revealing the fracture mechanism and establishing fracture criteria for shale rocks are fundamental issues in shale reservoir fracturing engineering. In this work, a comprehensive numerical, experimental, and theoretical study is conducted to investigate the anisotropic mixed mode I–II fracture behaviors of the Lushan shale under static and dynamic loading conditions. Two principal fracture orientations, i.e., Divider and Arrester, and four different inclination angles of notched semi-circular bending (NSCB) samples are considered for the fracture anisotropy analysis of shale. The dimensionless crack tip parameters and the <i>T</i> stress are determined via finite-element (FE) analysis and the over-determinist method. The experimental results reveal that the fracture properties of shale are significantly affected by its anisotropy and loading rate. The effective fracture toughness increases with increasing loading rate, and the Arrester type samples always hold higher fracture toughness values. High-speed digital image correlation (HS-DIC) and microscopic thin-section observations revealed that the Divider type samples exhibit classical mixed mode fracture behaviors, whereas unconventional kink angles occur in the Arrester type samples. Finally, using the newly developed semi-analytical generalized maximal tangential stress (SA-GMTS) criterion, which considers the rate-dependent fracture process zone (FPZ) length, the fracture behaviors of Divider type samples are successfully predicted. Furthermore, this work highlights the extension of the SA-GMTS criterion to anisotropic scenarios by considering anisotropic crack tip fields and rate-dependent fracture toughness values. The theoretical predictions based on the anisotropic SA-GMTS criterion agree very well with the experimental results of Arrester type fracture behaviors. The findings of this study provide a theoretical basis for the shale reservoir fracturing engineering.</p>