<p>The embedded bi-geomaterial interfaces are the potential sliding surfaces of accumulation landslides, critical in their initiation and reactivation. Focusing on the Huanggang area of China, where accumulation landslides are prevalent, the major failure patterns can be particularly categorized into overall failure along the deposit soil–bedrock interface (SRI) and localized failure along the native fracture surface of residual soil (RDI), dictating landslide severity and potential risk. Perceptively capturing the inadequate attention given to the relationship between the bi-geomaterial interface and failure pattern, this study comprehensively explores the contribution of physical–mechanical properties and field-scale morphological features employing experimental investigation, statistical analysis, and numerical simulation. Some fresh insights were recognized as follows: (1) The laboratory experiments indicate that the shear strength of RDI is slightly higher than that of SRI when saturated, implying the association of failure pattern with the rainfall. (2) The Maximal Information Coefficient (MIC)-based correlation analysis reveals that the potential sliding surface is moderately correlated with the curvature of the contact interface, providing data evidence. (3) The finite element seepage-deformation analyses of generalized landslide models with various field-scale morphological features indicate that an increasing curvature of interface (<i>K</i>) produces an elevated displacement and shifts the failure pattern from localized failure along RDI to overall failure along SRI. This study links the engineering aspects of bi-geomaterial to the potential failure pattern of accumulation landslides in a synthetical way, offering new insights for evaluating landslide severity using the provided survey data.</p>